diff --git a/base/serial/aux/Makefile b/base/serial/aux/Makefile
index 98807995..062a289d 100644
--- a/base/serial/aux/Makefile
+++ b/base/serial/aux/Makefile
@@ -3,8 +3,8 @@ include ../../../Make.inc
 # The object files
 #
 
-FOBJS  = isr.o isrx.o \
-	mrgsrt.o mrgsrtd.o isaperm.o ibsrch.o issrch.o  imsr.o imsrx.o
+FOBJS  = isr.o isrx.o msort_up.o msort_dw.o\
+	isaperm.o ibsrch.o issrch.o  imsr.o imsrx.o
 
 
 OBJS=$(FOBJS)
diff --git a/base/serial/aux/imsr.f90 b/base/serial/aux/imsr.f90
index 7032740f..a7d54e20 100644
--- a/base/serial/aux/imsr.f90
+++ b/base/serial/aux/imsr.f90
@@ -56,9 +56,9 @@ subroutine imsr(n,x,idir)
   endif
   
   if (idir==psb_sort_up_) then 
-    call mrgsrt(n,x,iaux,iret)
+    call msort_up(n,x,iaux,iret)
   else
-    call mrgsrtd(n,x,iaux,iret)
+    call msort_dw(n,x,iaux,iret)
   end if
   
   if (iret == 0) then 
diff --git a/base/serial/aux/imsrx.f90 b/base/serial/aux/imsrx.f90
index 8c7ee072..53eda348 100644
--- a/base/serial/aux/imsrx.f90
+++ b/base/serial/aux/imsrx.f90
@@ -64,9 +64,9 @@ subroutine imsrx(n,x,indx,idir,flag)
   endif
 
   if (idir == psb_sort_up_) then 
-    call mrgsrt(n,x,iaux,iret)
+    call msort_up(n,x,iaux,iret)
   else
-    call mrgsrtd(n,x,iaux,iret)
+    call msort_dw(n,x,iaux,iret)
   end if
 
   if (iret /= 1) then 
diff --git a/base/serial/aux/mrgsrt.f b/base/serial/aux/mrgsrt.f
deleted file mode 100644
index 89ecd289..00000000
--- a/base/serial/aux/mrgsrt.f
+++ /dev/null
@@ -1,234 +0,0 @@
-C
-C             Parallel Sparse BLAS  v2.0
-C   (C) Copyright 2006 Salvatore Filippone    University of Rome Tor Vergata
-C                      Alfredo Buttari        University of Rome Tor Vergata
-C
-C Redistribution and use in source and binary forms, with or without
-C modification, are permitted provided that the following conditions
-C are met:
-C   1. Redistributions of source code must retain the above copyright
-C      notice, this list of conditions and the following disclaimer.
-C   2. Redistributions in binary form must reproduce the above copyright
-C      notice, this list of conditions, and the following disclaimer in the
-C      documentation and/or other materials provided with the distribution.
-C   3. The name of the PSBLAS group or the names of its contributors may
-C      not be used to endorse or promote products derived from this
-C      software without specific written permission.
-C
-C THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-C ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
-C TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-C PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS
-C BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
-C CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
-C SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-C INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
-C CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-C ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-C POSSIBILITY OF SUCH DAMAGE.
-C
-C 
-***********************************************************************
-*                                                                     *
-*    FUNCTION = This subroutine returns an array of pointers, L,      *
-*               to be used to sort the integer input vector K;        *
-*               the routine implements a list merge-sort              *
-*                                                                     *
-***********************************************************************
-*                                                                     *
-*                CALL MRGSRT(N,K,L,IRET)                              *
-*                                                                     *
-*    INPUT =                                                          *
-*                                                                     *
-*       SYMBOLIC NAME: N                                              *
-*       POSITION:      First parameter.                               *
-*       ATTRIBUTES:    INTEGER                                        *
-*       VALUES:        >= 0                                           *
-*       DESCRIPTION:   Dimension of the array to be sorted            *
-*                                                                     *
-*       SYMBOLIC NAME: K                                              *
-*       POSITION:      Second parameter                               *
-*       ATTRIBUTES:    INTEGER  ARRAY(N)                              *
-*       VALUES:        Any                                            *
-*       DESCRIPTION:   Input array containing the keys, i.e., values  *
-*                      to be sorted                                   *
-*                                                                     *
-*                                                                     *
-*                                                                     *
-*    OUTPUT =                                                         *
-*                                                                     *
-*       SYMBOLIC NAME: L                                              *
-*       POSITION:      Third parameter                                *
-*       ATTRIBUTES:    INTEGER   ARRAY(N+2)                           *
-*       VALUES:        >= 0                                           *
-*       DESCRIPTION:   On exit, this array contains pointers to       *
-*                      the keys array.                                *
-*                                                                     *
-***********************************************************************
-***********************************************************************
-*                                                                     *
-***********************************************************************
-***********************************************************************
-*                ALGORITHM DESCRIPTION                                *
-*                                                                     *
-* REFERENCES  = (1) D. E. Knuth                                       *
-*                   The Art of Computer Programming,                  *
-*                     vol.3: Sorting and Searching                    *
-*                   Addison-Wesley, 1973                              *
-*                                                                     *
-* FUNCTION    = This subroutine is based on the well-known merge-sort *
-*               algorithm; according to (1) we are sorting 'records'  *
-*               R(I) with respect to keys K(I), and to this purpose   *
-*               we use 'links' L(I); at the end of the subroutine,    *
-*               L(0) is the index of the first record in the sorted   *
-*               sequence, then for every record R(I), we have into    *
-*               L(I) the index of the next one in the sequence. A     *
-*               value L(I)=0 signals the end of the sequence.         *
-*               The sorting is stable, i.e., if K(I)=K(J) and I<J,    *
-*               then in the sorted sequence R(I) precedes R(J); many  *
-*               sorting algorithms, e.g. quicksort, are not stable.   *
-*               The list merge-sort is one of the fastest stable      *
-*               sortings available; it is guaranteed to run in        *
-*               O(N log N) time on both the average and worst cases.  *
-*                                                                     *
-*                                                                     *
-***********************************************************************
-***********************************************************************
-*                ALGORITHM EXAMPLE(S)                                 *
-*                                                                     *
-* EXAMPLE: Construct a sorted array of records RS from a vector R     *
-*          according to the keys stored in K                          *
-*                                                                     *
-*          CALL MRGSRT(N,K,L,*100)                                    *
-*          I = L(0)                                                   *
-*          DO 100 J = 1, N                                            *
-*             RS(J) = R(I)                                            *
-*             I = L(I)                                                *
-* 100      CONTINUE     ! RETURN POINT IF ARRAY ALREADY SORTED        *
-*                                                                     *
-*                                                                     *
-* EXAMPLE: Sort in place array R                                      *
-*                                                                     *
-*          CALL MRGSRT(N,K,L,*400)                                    *
-*          LP = L(0)                                                  *
-*          KK = 1                                                     *
-* 100      CONTINUE                                                   *
-*          IF ((LP.EQ.0).OR.(KK.GT.N)) GOTO 400                       *
-* 200        CONTINUE                                                 *
-*            IF (LP.GE.KK) GOTO 300                                   *
-*            LP = L(LP)                                               *
-*            GOTO 200                                                 *
-* 300        CONTINUE                                                 *
-*            SWAP = R(KK)                                             *
-*            R(KK) = R(LP)                                            *
-*            R(LP) = SWAP                                             *
-*            LSWAP = L(LP)                                            *
-*            L(LP) = L(KK)                                            *
-*            L(KK) = LP                                               *
-*            LP    = LSWAP                                            *
-*            KK = KK+1                                                *
-*          GOTO 100                                                   *
-* 400      CONTINUE                                                   *
-*                                                                     *
-*                                                                     *
-***********************************************************************
-      SUBROUTINE MRGSRT(N,K,L,IRET)
-
-C     .. Scalar Arguments ..
-      INTEGER N, IRET
-C     ..
-C     .. Array Arguments ..
-      INTEGER K(N),L(0:N+1)
-C     ..
-C     .. Local Scalars ..
-      INTEGER P,Q,S,T
-C     ..
-C     .. Intrinsic Functions ..
-      INTRINSIC IABS,ISIGN
-C     ..
-      IRET = 0
-C  First step: we are preparing ordered sublists, exploiting
-C  what order was already in the input data; negative links
-C  mark the end of the sublists
-      L(0) = 1
-      T = N + 1
-      DO  P = 1,N - 1
-        IF (K(P).LE.K(P+1)) THEN
-          L(P) = P + 1
-        ELSE
-          L(T) = - (P+1)
-          T = P
-        END IF
-      END DO
-      L(T) = 0
-      L(N) = 0
-C See if the input was already sorted
-      IF (L(N+1).EQ.0) THEN
-        IRET = 1
-        RETURN 
-      ELSE
-        L(N+1) = IABS(L(N+1))
-      END IF
- 200  CONTINUE
-C Otherwise, begin a pass through the list.
-C Throughout all the subroutine we have:
-C  P, Q: pointing to the sublists being merged
-C  S: pointing to the most recently processed record
-C  T: pointing to the end of previously completed sublist
-      S = 0
-      T = N + 1
-      P = L(S)
-      Q = L(T)
-      IF (Q.EQ.0) RETURN
- 300  CONTINUE
-      IF (K(P).GT.K(Q)) GO TO 600
- 400  CONTINUE
-      L(S) = ISIGN(P,L(S))
-      S = P
-      P = L(P)
-      IF (P.GT.0)  GO TO 3100
-C  Otherwise, one sublist ended, and we append to it the rest
-C  of the other one.
- 500  CONTINUE
-      L(S) = Q
-      S = T
- 550  CONTINUE
-      T = Q
-      Q = L(Q)
-      IF (Q.GT.0) GO TO 550
-      GO TO 800
- 600  CONTINUE
-      L(S) = ISIGN(Q,L(S))
-      S = Q
-      Q = L(Q)
-      IF (Q.GT.0)  GO TO 3200
- 700  CONTINUE
-      L(S) = P
-      S = T
- 750  CONTINUE
-      T = P
-      P = L(P)
-      IF (P.GT.0) GO TO 750
- 800  CONTINUE
-      P = -P
-      Q = -Q
-      IF (Q.EQ.0) THEN
-        L(S) = ISIGN(P,L(S))
-        L(T) = 0
-        GO TO 200
-      ELSE
-        GO TO 300
-      END IF
- 3100 CONTINUE
-      IF (K(P).GT.K(Q)) GO TO 600
-      S = P
-      P = L(P)
-      IF (P.GT.0) GO TO 3100
-      GO TO 500
- 3200 CONTINUE
-      IF (K(P).LE.K(Q)) GO TO 400
-      S = Q
-      Q = L(Q)
-      IF (Q.GT.0) GO TO 3200
-      GO TO 700
-      END
diff --git a/base/serial/aux/mrgsrtd.f b/base/serial/aux/mrgsrtd.f
deleted file mode 100644
index b6064409..00000000
--- a/base/serial/aux/mrgsrtd.f
+++ /dev/null
@@ -1,234 +0,0 @@
-C
-C             Parallel Sparse BLAS  v2.0
-C   (C) Copyright 2006 Salvatore Filippone    University of Rome Tor Vergata
-C                      Alfredo Buttari        University of Rome Tor Vergata
-C
-C Redistribution and use in source and binary forms, with or without
-C modification, are permitted provided that the following conditions
-C are met:
-C   1. Redistributions of source code must retain the above copyright
-C      notice, this list of conditions and the following disclaimer.
-C   2. Redistributions in binary form must reproduce the above copyright
-C      notice, this list of conditions, and the following disclaimer in the
-C      documentation and/or other materials provided with the distribution.
-C   3. The name of the PSBLAS group or the names of its contributors may
-C      not be used to endorse or promote products derived from this
-C      software without specific written permission.
-C
-C THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-C ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
-C TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-C PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS
-C BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
-C CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
-C SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-C INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
-C CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-C ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-C POSSIBILITY OF SUCH DAMAGE.
-C
-C 
-***********************************************************************
-*                                                                     *
-*    FUNCTION = This subroutine returns an array of pointers, L,      *
-*               to be used to sort the integer input vector K;        *
-*               the routine implements a list merge-sort              *
-*                                                                     *
-***********************************************************************
-*                                                                     *
-*                CALL MRGSRTD(N,K,L,IRET)                             *
-*                                                                     *
-*    INPUT =                                                          *
-*                                                                     *
-*       SYMBOLIC NAME: N                                              *
-*       POSITION:      First parameter.                               *
-*       ATTRIBUTES:    INTEGER                                        *
-*       VALUES:        >= 0                                           *
-*       DESCRIPTION:   Dimension of the array to be sorted            *
-*                                                                     *
-*       SYMBOLIC NAME: K                                              *
-*       POSITION:      Second parameter                               *
-*       ATTRIBUTES:    INTEGER  ARRAY(N)                              *
-*       VALUES:        Any                                            *
-*       DESCRIPTION:   Input array containing the keys, i.e., values  *
-*                      to be sorted                                   *
-*                                                                     *
-*                                                                     *
-*                                                                     *
-*    OUTPUT =                                                         *
-*                                                                     *
-*       SYMBOLIC NAME: L                                              *
-*       POSITION:      Third parameter                                *
-*       ATTRIBUTES:    INTEGER   ARRAY(N+2)                           *
-*       VALUES:        >= 0                                           *
-*       DESCRIPTION:   On exit, this array contains pointers to       *
-*                      the keys array.                                *
-*                                                                     *
-***********************************************************************
-***********************************************************************
-*                                                                     *
-***********************************************************************
-***********************************************************************
-*                ALGORITHM DESCRIPTION                                *
-*                                                                     *
-* REFERENCES  = (1) D. E. Knuth                                       *
-*                   The Art of Computer Programming,                  *
-*                     vol.3: Sorting and Searching                    *
-*                   Addison-Wesley, 1973                              *
-*                                                                     *
-* FUNCTION    = This subroutine is based on the well-known merge-sort *
-*               algorithm; according to (1) we are sorting 'records'  *
-*               R(I) with respect to keys K(I), and to this purpose   *
-*               we use 'links' L(I); at the end of the subroutine,    *
-*               L(0) is the index of the first record in the sorted   *
-*               sequence, then for every record R(I), we have into    *
-*               L(I) the index of the next one in the sequence. A     *
-*               value L(I)=0 signals the end of the sequence.         *
-*               The sorting is stable, i.e., if K(I)=K(J) and I<J,    *
-*               then in the sorted sequence R(I) precedes R(J); many  *
-*               sorting algorithms, e.g. quicksort, are not stable.   *
-*               The list merge-sort is one of the fastest stable      *
-*               sortings available; it is guaranteed to run in        *
-*               O(N log N) time on both the average and worst cases.  *
-*                                                                     *
-*                                                                     *
-***********************************************************************
-***********************************************************************
-*                ALGORITHM EXAMPLE(S)                                 *
-*                                                                     *
-* EXAMPLE: Construct a sorted array of records RS from a vector R     *
-*          according to the keys stored in K                          *
-*                                                                     *
-*          CALL MRGSRTD(N,K,L,*100)                                   *
-*          I = L(0)                                                   *
-*          DO 100 J = 1, N                                            *
-*             RS(J) = R(I)                                            *
-*             I = L(I)                                                *
-* 100      CONTINUE     ! RETURN POINT IF ARRAY ALREADY SORTED        *
-*                                                                     *
-*                                                                     *
-* EXAMPLE: Sort in place array R                                      *
-*                                                                     *
-*          CALL MRGSRTD(N,K,L,*400)                                   *
-*          LP = L(0)                                                  *
-*          KK = 1                                                     *
-* 100      CONTINUE                                                   *
-*          IF ((LP.EQ.0).OR.(KK.GT.N)) GOTO 400                       *
-* 200        CONTINUE                                                 *
-*            IF (LP.GE.KK) GOTO 300                                   *
-*            LP = L(LP)                                               *
-*            GOTO 200                                                 *
-* 300        CONTINUE                                                 *
-*            SWAP = R(KK)                                             *
-*            R(KK) = R(LP)                                            *
-*            R(LP) = SWAP                                             *
-*            LSWAP = L(LP)                                            *
-*            L(LP) = L(KK)                                            *
-*            L(KK) = LP                                               *
-*            LP    = LSWAP                                            *
-*            KK = KK+1                                                *
-*          GOTO 100                                                   *
-* 400      CONTINUE                                                   *
-*                                                                     *
-*                                                                     *
-***********************************************************************
-      SUBROUTINE MRGSRTD(N,K,L,IRET)
-
-C     .. Scalar Arguments ..
-      INTEGER N, IRET
-C     ..
-C     .. Array Arguments ..
-      INTEGER K(N),L(0:N+1)
-C     ..
-C     .. Local Scalars ..
-      INTEGER P,Q,S,T
-C     ..
-C     .. Intrinsic Functions ..
-      INTRINSIC IABS,ISIGN
-C     ..
-      IRET = 0
-C  First step: we are preparing ordered sublists, exploiting
-C  what order was already in the input data; negative links
-C  mark the end of the sublists
-      L(0) = 1
-      T = N + 1
-      DO  P = 1,N - 1
-        IF (K(P).GE.K(P+1)) THEN
-          L(P) = P + 1
-        ELSE
-          L(T) = - (P+1)
-          T = P
-        END IF
-      END DO
-      L(T) = 0
-      L(N) = 0
-C See if the input was already sorted
-      IF (L(N+1).EQ.0) THEN
-        IRET = 1
-        RETURN 
-      ELSE
-        L(N+1) = IABS(L(N+1))
-      END IF
- 200  CONTINUE
-C Otherwise, begin a pass through the list.
-C Throughout all the subroutine we have:
-C  P, Q: pointing to the sublists being merged
-C  S: pointing to the most recently processed record
-C  T: pointing to the end of previously completed sublist
-      S = 0
-      T = N + 1
-      P = L(S)
-      Q = L(T)
-      IF (Q.EQ.0) RETURN
- 300  CONTINUE
-      IF (K(P).LT.K(Q)) GO TO 600
- 400  CONTINUE
-      L(S) = ISIGN(P,L(S))
-      S = P
-      P = L(P)
-      IF (P.GT.0)  GO TO 3100
-C  Otherwise, one sublist ended, and we append to it the rest
-C  of the other one.
- 500  CONTINUE
-      L(S) = Q
-      S = T
- 550  CONTINUE
-      T = Q
-      Q = L(Q)
-      IF (Q.GT.0) GO TO 550
-      GO TO 800
- 600  CONTINUE
-      L(S) = ISIGN(Q,L(S))
-      S = Q
-      Q = L(Q)
-      IF (Q.GT.0)  GO TO 3200
- 700  CONTINUE
-      L(S) = P
-      S = T
- 750  CONTINUE
-      T = P
-      P = L(P)
-      IF (P.GT.0) GO TO 750
- 800  CONTINUE
-      P = -P
-      Q = -Q
-      IF (Q.EQ.0) THEN
-        L(S) = ISIGN(P,L(S))
-        L(T) = 0
-        GO TO 200
-      ELSE
-        GO TO 300
-      END IF
- 3100 CONTINUE
-      IF (K(P).LT.K(Q)) GO TO 600
-      S = P
-      P = L(P)
-      IF (P.GT.0) GO TO 3100
-      GO TO 500
- 3200 CONTINUE
-      IF (K(P).GE.K(Q)) GO TO 400
-      S = Q
-      Q = L(Q)
-      IF (Q.GT.0) GO TO 3200
-      GO TO 700
-      END
diff --git a/base/serial/aux/msort_dw.f90 b/base/serial/aux/msort_dw.f90
new file mode 100644
index 00000000..527952ff
--- /dev/null
+++ b/base/serial/aux/msort_dw.f90
@@ -0,0 +1,170 @@
+!
+!             Parallel Sparse BLAS  v2.0
+!   (C) Copyright 2006 Salvatore Filippone    University of Rome Tor Vergata
+!                      Alfredo Buttari        University of Rome Tor Vergata
+!
+! Redistribution and use in source and binary forms, with or without
+! modification, are permitted provided that the following conditions
+! are met:
+!   1. Redistributions of source code must retain the above copyright
+!      notice, this list of conditions and the following disclaimer.
+!   2. Redistributions in binary form must reproduce the above copyright
+!      notice, this list of conditions, and the following disclaimer in the
+!      documentation and/or other materials provided with the distribution.
+!   3. The name of the PSBLAS group or the names of its contributors may
+!      not be used to endorse or promote products derived from this
+!      software without specific written permission.
+!
+! THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+! ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+! TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+! PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS
+! BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+! CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+! SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+! INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+! CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+! ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+! POSSIBILITY OF SUCH DAMAGE.
+!
+! File:  msort_dw.f90
+!
+! Subroutine: msort_dw
+!   This subroutine sorts an integer array into ascending order.
+!
+! Parameters:
+!   n         -  integer                   Input: size of the array 
+!   k         -  integer(*)                input: array of keys to be sorted
+!   l         -  integer(0:n+1)           output: link list 
+!   iret      -  integer                  output: 0 Normal termination
+!                                                 1 the array was already sorted 
+!                                                                     *
+! REFERENCES  = (1) D. E. Knuth                                       *
+!                   The Art of Computer Programming,                  *
+!                     vol.3: Sorting and Searching                    *
+!                   Addison-Wesley, 1973                              *
+!                                                                     *
+!  call msort_dw(n,x,iaux,iret)
+!  
+!  if (iret == 0) then 
+!    lp = iaux(0)
+!    k  = 1
+!    do 
+!      if ((lp==0).or.(k>n)) exit
+!      do 
+!        if (lp >= k) exit
+!        lp = iaux(lp)
+!      end do
+!      iswap    = x(lp)
+!      x(lp)    = x(k)
+!      x(k)     = iswap
+!      lswap    = iaux(lp)
+!      iaux(lp) = iaux(k)
+!      iaux(k)  = lp
+!      lp = lswap 
+!      k  = k + 1
+!    enddo
+!  end if
+!
+!
+subroutine msort_dw(n,k,l,iret)
+  integer n, iret
+  integer k(n),l(0:n+1)
+  !
+  integer p,q,s,t
+  intrinsic iabs,isign
+  !     ..
+  iret = 0
+  !  first step: we are preparing ordered sublists, exploiting
+  !  what order was already in the input data; negative links
+  !  mark the end of the sublists
+  l(0) = 1
+  t = n + 1
+  do  p = 1,n - 1
+    if (k(p) >= k(p+1)) then
+      l(p) = p + 1
+    else
+      l(t) = - (p+1)
+      t = p
+    end if
+  end do
+  l(t) = 0
+  l(n) = 0
+  ! see if the input was already sorted
+  if (l(n+1) == 0) then
+    iret = 1
+    return 
+  else
+    l(n+1) = iabs(l(n+1))
+  end if
+
+  mergepass: do 
+    ! otherwise, begin a pass through the list.
+    ! throughout all the subroutine we have:
+    !  p, q: pointing to the sublists being merged
+    !  s: pointing to the most recently processed record
+    !  t: pointing to the end of previously completed sublist
+    s = 0
+    t = n + 1
+    p = l(s)
+    q = l(t)
+    if (q == 0) exit mergepass
+
+    outer: do 
+
+      if (k(p) < k(q)) then 
+
+        l(s) = isign(q,l(s))
+        s = q
+        q = l(q)
+        if (q > 0) then 
+          do 
+            if (k(p) >= k(q)) cycle outer
+            s = q
+            q = l(q)
+            if (q <= 0) exit
+          end do
+        end if
+        l(s) = p
+        s = t
+        do 
+          t = p
+          p = l(p)
+          if (p <= 0) exit
+        end do
+
+      else 
+
+        l(s) = isign(p,l(s))
+        s = p
+        p = l(p)
+        if (p>0) then 
+          do 
+            if (k(p) < k(q)) cycle outer 
+            s = p
+            p = l(p)
+            if (p <= 0) exit
+          end do
+        end if
+        !  otherwise, one sublist ended, and we append to it the rest
+        !  of the other one.
+        l(s) = q
+        s = t
+        do 
+          t = q
+          q = l(q)
+          if (q <= 0) exit
+        end do
+      end if
+
+      p = -p
+      q = -q
+      if (q == 0) then
+        l(s) = isign(p,l(s))
+        l(t) = 0
+        exit outer 
+      end if
+    end do outer
+  end do mergepass
+
+end subroutine msort_dw
diff --git a/base/serial/aux/msort_up.f90 b/base/serial/aux/msort_up.f90
new file mode 100644
index 00000000..4c10b11c
--- /dev/null
+++ b/base/serial/aux/msort_up.f90
@@ -0,0 +1,170 @@
+!
+!             Parallel Sparse BLAS  v2.0
+!   (C) Copyright 2006 Salvatore Filippone    University of Rome Tor Vergata
+!                      Alfredo Buttari        University of Rome Tor Vergata
+!
+! Redistribution and use in source and binary forms, with or without
+! modification, are permitted provided that the following conditions
+! are met:
+!   1. Redistributions of source code must retain the above copyright
+!      notice, this list of conditions and the following disclaimer.
+!   2. Redistributions in binary form must reproduce the above copyright
+!      notice, this list of conditions, and the following disclaimer in the
+!      documentation and/or other materials provided with the distribution.
+!   3. The name of the PSBLAS group or the names of its contributors may
+!      not be used to endorse or promote products derived from this
+!      software without specific written permission.
+!
+! THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+! ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+! TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+! PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS
+! BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+! CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+! SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+! INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+! CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+! ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+! POSSIBILITY OF SUCH DAMAGE.
+!
+! File:  msort_up.f90
+!
+! Subroutine: msort_up
+!   This subroutine sorts an integer array into ascending order.
+!
+! Parameters:
+!   n         -  integer                   Input: size of the array 
+!   k         -  integer(*)                input: array of keys to be sorted
+!   l         -  integer(0:n+1)           output: link list 
+!   iret      -  integer                  output: 0 Normal termination
+!                                                 1 the array was already sorted 
+!                                                                     *
+! REFERENCES  = (1) D. E. Knuth                                       *
+!                   The Art of Computer Programming,                  *
+!                     vol.3: Sorting and Searching                    *
+!                   Addison-Wesley, 1973                              *
+!                                                                     *
+!  call msort_up(n,x,iaux,iret)
+!  
+!  if (iret == 0) then 
+!    lp = iaux(0)
+!    k  = 1
+!    do 
+!      if ((lp==0).or.(k>n)) exit
+!      do 
+!        if (lp >= k) exit
+!        lp = iaux(lp)
+!      end do
+!      iswap    = x(lp)
+!      x(lp)    = x(k)
+!      x(k)     = iswap
+!      lswap    = iaux(lp)
+!      iaux(lp) = iaux(k)
+!      iaux(k)  = lp
+!      lp = lswap 
+!      k  = k + 1
+!    enddo
+!  end if
+!
+!
+subroutine msort_up(n,k,l,iret)
+  integer n, iret
+  integer k(n),l(0:n+1)
+  !
+  integer p,q,s,t
+  intrinsic iabs,isign
+  !     ..
+  iret = 0
+  !  first step: we are preparing ordered sublists, exploiting
+  !  what order was already in the input data; negative links
+  !  mark the end of the sublists
+  l(0) = 1
+  t = n + 1
+  do  p = 1,n - 1
+    if (k(p) <= k(p+1)) then
+      l(p) = p + 1
+    else
+      l(t) = - (p+1)
+      t = p
+    end if
+  end do
+  l(t) = 0
+  l(n) = 0
+  ! see if the input was already sorted
+  if (l(n+1) == 0) then
+    iret = 1
+    return 
+  else
+    l(n+1) = iabs(l(n+1))
+  end if
+
+  mergepass: do 
+    ! otherwise, begin a pass through the list.
+    ! throughout all the subroutine we have:
+    !  p, q: pointing to the sublists being merged
+    !  s: pointing to the most recently processed record
+    !  t: pointing to the end of previously completed sublist
+    s = 0
+    t = n + 1
+    p = l(s)
+    q = l(t)
+    if (q == 0) exit mergepass
+
+    outer: do 
+
+      if (k(p) > k(q)) then 
+
+        l(s) = isign(q,l(s))
+        s = q
+        q = l(q)
+        if (q > 0) then 
+          do 
+            if (k(p) <= k(q)) cycle outer
+            s = q
+            q = l(q)
+            if (q <= 0) exit
+          end do
+        end if
+        l(s) = p
+        s = t
+        do 
+          t = p
+          p = l(p)
+          if (p <= 0) exit
+        end do
+
+      else 
+
+        l(s) = isign(p,l(s))
+        s = p
+        p = l(p)
+        if (p>0) then 
+          do 
+            if (k(p) > k(q)) cycle outer 
+            s = p
+            p = l(p)
+            if (p <= 0) exit
+          end do
+        end if
+        !  otherwise, one sublist ended, and we append to it the rest
+        !  of the other one.
+        l(s) = q
+        s = t
+        do 
+          t = q
+          q = l(q)
+          if (q <= 0) exit
+        end do
+      end if
+
+      p = -p
+      q = -q
+      if (q == 0) then
+        l(s) = isign(p,l(s))
+        l(t) = 0
+        exit outer 
+      end if
+    end do outer
+  end do mergepass
+
+end subroutine msort_up
diff --git a/base/serial/dp/dcoco.f b/base/serial/dp/dcoco.f
index 05b9802e..b1eddbf0 100644
--- a/base/serial/dp/dcoco.f
+++ b/base/serial/dp/dcoco.f
@@ -147,7 +147,7 @@ c
             if (debug) write(0,*) 'build check :',ia2n(ip1+psb_nnzt_) 
             
 c     .... order with key ia1n ...
-            call mrgsrt(nnz,ia1n,aux,iret)
+            call msort_up(nnz,ia1n,aux,iret)
             if (iret.eq.0) call reordvn3(nnz,arn,ia1n,ia2n,aux(ipx),aux)
 c     .... order with key ia2n ...
             
@@ -159,7 +159,7 @@ c     .... order with key ia2n ...
                 j = j+1
               enddo
               nzl = j - i
-              call mrgsrt(nzl,ia2n(i),aux,iret)
+              call msort_up(nzl,ia2n(i),aux,iret)
               if (iret.eq.0) call reordvn3(nzl,arn(i),ia1n(i),ia2n(i),
      +          aux(ipx+i-1),aux)
               i = j
@@ -198,7 +198,7 @@ c     ... add the duplicated element ...
           else
             
 c     .... order with key ia1n ...
-            call mrgsrt(nnz,ia1n,aux,iret)
+            call msort_up(nnz,ia1n,aux,iret)
             if (iret.eq.0) call reordvn(nnz,arn,ia1n,ia2n,aux)
 c     .... order with key ia2n ...
             
@@ -210,7 +210,7 @@ c     .... order with key ia2n ...
                 j = j+1
               enddo
               nzl = j - i
-              call mrgsrt(nzl,ia2n(i),aux,iret)
+              call msort_up(nzl,ia2n(i),aux,iret)
               if (iret.eq.0) call reordvn(nzl,arn(i),ia1n(i),ia2n(i),
      +          aux)
               i = j
diff --git a/base/serial/dp/dcocr.f b/base/serial/dp/dcocr.f
index 01e5d044..1d07f587 100644
--- a/base/serial/dp/dcocr.f
+++ b/base/serial/dp/dcocr.f
@@ -157,7 +157,7 @@ c$$$     +        ip1,ip2,nnz,ian2(ip1+nnzt_)
 
             if (debug) write(0,*) 'Build check :',ian2(ip1+psb_nnzt_) 
 C       .... Order with key IA ...
-            CALL MRGSRT(NNZ,IA,AUX,IRET)
+            CALL MSORT_UP(NNZ,IA,AUX,IRET)
             IF (IRET.EQ.0) CALL REORDVN3(NNZ,AR,IA,JA,AUX(IPX),AUX)
             if (debug) then 
               do i=1, nnz-1
@@ -183,7 +183,7 @@ c$$$     +          (J.LE.NNZ))
                 J = J+1
               ENDDO
               NZL = J - I
-              CALL MRGSRT(NZL,JA(I),AUX,IRET)
+              CALL MSORT_UP(NZL,JA(I),AUX,IRET)
               IF (IRET.EQ.0) CALL REORDVN3(NZL,AR(I),IA(I),JA(I),
      +          AUX(IPX+I-1),AUX)
               I = J
@@ -250,7 +250,7 @@ C                    ... Sum the duplicated element ...
           ELSE
 c$$$            write(0,*) 'Going for ELSE !!!?'
 C       .... Order with key IA ...
-            CALL MRGSRT(NNZ,IA,AUX,IRET)
+            CALL MSORT_UP(NNZ,IA,AUX,IRET)
             IF (IRET.EQ.0) CALL REORDVN(NNZ,AR,IA,JA,AUX)
 C       .... Order with key IA2N ...
             I    = 1
@@ -266,7 +266,7 @@ c$$$     +          (J.LE.NNZ))
                 J = J+1
               ENDDO
               NZL = J - I
-              CALL MRGSRT(NZL,JA(I),AUX,IRET)
+              CALL MSORT_UP(NZL,JA(I),AUX,IRET)
               IF (IRET.EQ.0) CALL REORDVN(NZL,AR(I),IA(I),JA(I),AUX)
               I = J
             ENDDO
@@ -343,7 +343,7 @@ c$$$          endif
         ELSE IF (DESCRA(1:1).EQ.'T' .AND. DESCRA(2:2).EQ.'U') THEN
 
 C       .... Order with key IA ...
-          CALL MRGSRT(NNZ,IA,AUX,IRET)
+          CALL MSORT_UP(NNZ,IA,AUX,IRET)
           IF (IRET.EQ.0) CALL REORDVN(NNZ,AR,IA,JA,AUX)
 C       .... Order with key IA2N ...
           I    = 1
@@ -359,7 +359,7 @@ c$$$     +          (J.LE.NNZ))
               J = J+1
             ENDDO
             NZL = J - I
-            CALL MRGSRT(NZL,JA(I),AUX,IRET)
+            CALL MSORT_UP(NZL,JA(I),AUX,IRET)
             IF (IRET.EQ.0) CALL REORDVN(NZL,AR(I),IA(I),JA(I),AUX)
             I = J
           ENDDO
@@ -443,7 +443,7 @@ C     ... Sum the duplicated element ...
         ELSE IF (DESCRA(1:1).EQ.'T' .AND. DESCRA(2:2).EQ.'L') THEN
 
 C       .... Order with key IA ...
-          CALL MRGSRT(NNZ,IA,AUX,IRET)
+          CALL MSORT_UP(NNZ,IA,AUX,IRET)
           IF (IRET.EQ.0) CALL REORDVN(NNZ,AR,IA,JA,AUX)
 C       .... Order with key IA2N ...
           I    = 1
@@ -459,7 +459,7 @@ c$$$     +          (J.LE.NNZ))
               J = J+1
             ENDDO
             NZL = J - I
-            CALL MRGSRT(NZL,JA(I),AUX,IRET)
+            CALL MSORT_UP(NZL,JA(I),AUX,IRET)
             IF (IRET.EQ.0) CALL REORDVN(NZL,AR(I),IA(I),JA(I),AUX)
             I = J
           ENDDO
diff --git a/base/serial/dp/dgblock.f b/base/serial/dp/dgblock.f
index 22871096..7dfd51b4 100644
--- a/base/serial/dp/dgblock.f
+++ b/base/serial/dp/dgblock.f
@@ -53,7 +53,7 @@ C     Compute number of nnzero elements per row
 C     Sorting Array work
 C ........................
 
-      CALL MRGSRT(M,WORK,WORK(M+1),IRET)
+      CALL MSORT_UP(M,WORK,WORK(M+1),IRET)
       IF (IRET.EQ.0) THEN
 C     Construct IPERM Vector
         LP = WORK(M+1)
diff --git a/base/serial/dp/djdcox.f b/base/serial/dp/djdcox.f
index 87772e17..317b3bc2 100755
--- a/base/serial/dp/djdcox.f
+++ b/base/serial/dp/djdcox.f
@@ -132,7 +132,7 @@ C     SCALE  = (UNITD.EQ.'L') ! meaningless
             
             
 C     .... Order with key IA1N....
-            CALL MRGSRT(NNZ,IA1N,AUX,IRET)
+            CALL MSORT_UP(NNZ,IA1N,AUX,IRET)
             IF (IRET.EQ.0) CALL REORDVN(NNZ,ARN,IA1N,IA2N,AUX)           
             
 C     .... Order with key IA2N ...
@@ -144,7 +144,7 @@ C     .... Order with key IA2N ...
                   J = J+1
                ENDDO
                NZL = J - I
-               CALL MRGSRT(NZL,IA2N(I),AUX,IRET)
+               CALL MSORT_UP(NZL,IA2N(I),AUX,IRET)
                IF (IRET.EQ.0) CALL REORDVN(NZL,ARN(I),IA1N(I),IA2N(I),
      +              AUX)
                I = J
diff --git a/base/serial/dp/dvtfg.f b/base/serial/dp/dvtfg.f
index a1ce5192..0e1165a3 100644
--- a/base/serial/dp/dvtfg.f
+++ b/base/serial/dp/dvtfg.f
@@ -160,7 +160,7 @@ C               FOR CURRENT GROUP
 C                                                                               
             L1 = IWORK2(LEV+1) - IWORK2(LEV)                                    
             L0 = IWORK2(LEV) - 1                                                
-            CALL MRGSRT(L1,IWORK1(IWORK2(LEV)),IPAT,IRET)                        
+            CALL MSORT_UP(L1,IWORK1(IWORK2(LEV)),IPAT,IRET)                        
             IF (IRET.EQ.0) THEN
               NP = IPAT(1)                                                        
               DO 280 L = 1, L1                                                    
diff --git a/base/serial/dp/zcoco.f b/base/serial/dp/zcoco.f
index f79cced9..81c7e58b 100644
--- a/base/serial/dp/zcoco.f
+++ b/base/serial/dp/zcoco.f
@@ -146,7 +146,7 @@ c
             if (debug) write(0,*) 'build check :',ia2n(ip1+psb_nnzt_) 
             
 c     .... order with key ia1n ...
-            call mrgsrt(nnz,ia1n,aux,iret)
+            call msort_up(nnz,ia1n,aux,iret)
             if (iret.eq.0)
      +        call zreordvn3(nnz,arn,ia1n,ia2n,aux(ipx),aux)
 c     .... order with key ia2n ...
@@ -159,7 +159,7 @@ c     .... order with key ia2n ...
                 j = j+1
               enddo
               nzl = j - i
-              call mrgsrt(nzl,ia2n(i),aux,iret)
+              call msort_up(nzl,ia2n(i),aux,iret)
               if (iret.eq.0) call zreordvn3(nzl,arn(i),ia1n(i),ia2n(i),
      +          aux(ipx+i-1),aux)
               i = j
@@ -198,7 +198,7 @@ c     ... sum the duplicated element ...
           else
             
 c     .... order with key ia1n ...
-            call mrgsrt(nnz,ia1n,aux,iret)
+            call msort_up(nnz,ia1n,aux,iret)
             if (iret.eq.0) call zreordvn(nnz,arn,ia1n,ia2n,aux)
 c     .... order with key ia2n ...
             
@@ -210,7 +210,7 @@ c     .... order with key ia2n ...
                 j = j+1
               enddo
               nzl = j - i
-              call mrgsrt(nzl,ia2n(i),aux,iret)
+              call msort_up(nzl,ia2n(i),aux,iret)
               if (iret.eq.0) call zreordvn(nzl,arn(i),ia1n(i),ia2n(i),
      +          aux)
               i = j
diff --git a/base/serial/dp/zcocr.f b/base/serial/dp/zcocr.f
index 6475315e..90f12733 100644
--- a/base/serial/dp/zcocr.f
+++ b/base/serial/dp/zcocr.f
@@ -157,7 +157,7 @@ c$$$     +        ip1,ip2,nnz,ian2(ip1+nnzt_)
 
             if (debug) write(0,*) 'Build check :',ian2(ip1+psb_nnzt_) 
 C       .... Order with key IA ...
-            CALL MRGSRT(NNZ,IA,AUX,IRET)
+            CALL MSORT_UP(NNZ,IA,AUX,IRET)
             IF (IRET.EQ.0) CALL ZREORDVN3(NNZ,AR,IA,JA,AUX(IPX),AUX)
             if (debug) then 
               do i=1, nnz-1
@@ -183,7 +183,7 @@ c$$$     +          (J.LE.NNZ))
                 J = J+1
               ENDDO
               NZL = J - I
-              CALL MRGSRT(NZL,JA(I),AUX,IRET)
+              CALL MSORT_UP(NZL,JA(I),AUX,IRET)
               IF (IRET.EQ.0) CALL ZREORDVN3(NZL,AR(I),IA(I),JA(I),
      +          AUX(IPX+I-1),AUX)
               I = J
@@ -244,7 +244,7 @@ C                    ... Sum the duplicated element ...
           ELSE
 c$$$            write(0,*) 'Going for ELSE !!!?'
 C       .... Order with key IA ...
-            CALL MRGSRT(NNZ,IA,AUX,IRET)
+            CALL MSORT_UP(NNZ,IA,AUX,IRET)
             IF (IRET.EQ.0) CALL ZREORDVN(NNZ,AR,IA,JA,AUX)
 C       .... Order with key IA2N ...
             I    = 1
@@ -260,7 +260,7 @@ c$$$     +          (J.LE.NNZ))
                 J = J+1
               ENDDO
               NZL = J - I
-              CALL MRGSRT(NZL,JA(I),AUX,IRET)
+              CALL MSORT_UP(NZL,JA(I),AUX,IRET)
               IF (IRET.EQ.0) CALL ZREORDVN(NZL,AR(I),IA(I),JA(I),AUX)
               I = J
             ENDDO
@@ -337,7 +337,7 @@ C                    ... Sum the duplicated element ...
         ELSE IF (DESCRA(1:1).EQ.'T' .AND. DESCRA(2:2).EQ.'U') THEN
 
 C       .... Order with key IA ...
-          CALL MRGSRT(NNZ,IA,AUX,IRET)
+          CALL MSORT_UP(NNZ,IA,AUX,IRET)
           IF (IRET.EQ.0) CALL ZREORDVN(NNZ,AR,IA,JA,AUX)
 C       .... Order with key IA2N ...
           I    = 1
@@ -353,7 +353,7 @@ c$$$     +          (J.LE.NNZ))
               J = J+1
             ENDDO
             NZL = J - I
-            CALL MRGSRT(NZL,JA(I),AUX,IRET)
+            CALL MSORT_UP(NZL,JA(I),AUX,IRET)
             IF (IRET.EQ.0) CALL ZREORDVN(NZL,AR(I),IA(I),JA(I),AUX)
             I = J
           ENDDO
@@ -437,7 +437,7 @@ C     ... Sum the duplicated element ...
         ELSE IF (DESCRA(1:1).EQ.'T' .AND. DESCRA(2:2).EQ.'L') THEN
 
 C       .... Order with key IA ...
-          CALL MRGSRT(NNZ,IA,AUX,IRET)
+          CALL MSORT_UP(NNZ,IA,AUX,IRET)
           IF (IRET.EQ.0) CALL ZREORDVN(NNZ,AR,IA,JA,AUX)
 C       .... Order with key IA2N ...
           I    = 1
@@ -453,7 +453,7 @@ c$$$     +          (J.LE.NNZ))
               J = J+1
             ENDDO
             NZL = J - I
-            CALL MRGSRT(NZL,JA(I),AUX,IRET)
+            CALL MSORT_UP(NZL,JA(I),AUX,IRET)
             IF (IRET.EQ.0) CALL ZREORDVN(NZL,AR(I),IA(I),JA(I),AUX)
             I = J
           ENDDO
diff --git a/base/serial/psb_dfixcoo.f90 b/base/serial/psb_dfixcoo.f90
index 877c45ce..a0488f24 100644
--- a/base/serial/psb_dfixcoo.f90
+++ b/base/serial/psb_dfixcoo.f90
@@ -72,7 +72,7 @@ Subroutine psb_dfixcoo(A,INFO,idir)
 
   case(0) !  Row major order
 
-    call mrgsrt(nza,a%ia1(1),iaux(1),iret)
+    call msort_up(nza,a%ia1(1),iaux(1),iret)
     if (iret.eq.0) call reordvn(nza,a%aspk(1),a%ia1(1),a%ia2(1),iaux(1))
     i    = 1
     j    = i
@@ -82,7 +82,7 @@ Subroutine psb_dfixcoo(A,INFO,idir)
         if (j > nza) exit
       enddo
       nzl = j - i
-      call mrgsrt(nzl,a%ia2(i),iaux(1),iret)
+      call msort_up(nzl,a%ia2(i),iaux(1),iret)
       if (iret.eq.0) &
            & call reordvn(nzl,a%aspk(i),a%ia1(i),a%ia2(i),iaux(1))
       i = j
@@ -113,7 +113,7 @@ Subroutine psb_dfixcoo(A,INFO,idir)
 
   case(1) !  Col major order
 
-    call mrgsrt(nza,a%ia2(1),iaux(1),iret)
+    call msort_up(nza,a%ia2(1),iaux(1),iret)
     if (iret.eq.0) call reordvn(nza,a%aspk(1),a%ia1(1),a%ia2(1),iaux(1))
     i    = 1
     j    = i
@@ -123,7 +123,7 @@ Subroutine psb_dfixcoo(A,INFO,idir)
         if (j > nza) exit
       enddo
       nzl = j - i
-      call mrgsrt(nzl,a%ia1(i),iaux(1),iret)
+      call msort_up(nzl,a%ia1(i),iaux(1),iret)
       if (iret.eq.0) &
            & call reordvn(nzl,a%aspk(i),a%ia1(i),a%ia2(i),iaux(1))
       i = j
diff --git a/base/serial/psb_zfixcoo.f90 b/base/serial/psb_zfixcoo.f90
index 5b669d43..95a76518 100644
--- a/base/serial/psb_zfixcoo.f90
+++ b/base/serial/psb_zfixcoo.f90
@@ -72,7 +72,7 @@ Subroutine psb_zfixcoo(A,INFO,idir)
 
   case(0) !  Row major order
 
-    call mrgsrt(nza,a%ia1(1),iaux(1),iret)
+    call msort_up(nza,a%ia1(1),iaux(1),iret)
     if (iret.eq.0) call zreordvn(nza,a%aspk(1),a%ia1(1),a%ia2(1),iaux(1))
     i    = 1
     j    = i
@@ -82,7 +82,7 @@ Subroutine psb_zfixcoo(A,INFO,idir)
         if (j > nza) exit
       enddo
       nzl = j - i
-      call mrgsrt(nzl,a%ia2(i),iaux(1),iret)
+      call msort_up(nzl,a%ia2(i),iaux(1),iret)
       if (iret.eq.0) &
            & call zreordvn(nzl,a%aspk(i),a%ia1(i),a%ia2(i),iaux(1))
       i = j
@@ -113,7 +113,7 @@ Subroutine psb_zfixcoo(A,INFO,idir)
 
   case(1) !  Col major order
 
-    call mrgsrt(nza,a%ia2(1),iaux(1),iret)
+    call msort_up(nza,a%ia2(1),iaux(1),iret)
     if (iret.eq.0) call zreordvn(nza,a%aspk(1),a%ia1(1),a%ia2(1),iaux(1))
     i    = 1
     j    = i
@@ -123,7 +123,7 @@ Subroutine psb_zfixcoo(A,INFO,idir)
         if (j > nza) exit
       enddo
       nzl = j - i
-      call mrgsrt(nzl,a%ia1(i),iaux(1),iret)
+      call msort_up(nzl,a%ia1(i),iaux(1),iret)
       if (iret.eq.0) &
            & call zreordvn(nzl,a%aspk(i),a%ia1(i),a%ia2(i),iaux(1))
       i = j