diff --git a/base/modules/serial/psb_c_base_vect_mod.F90 b/base/modules/serial/psb_c_base_vect_mod.F90
index 793df3bc..a4772103 100644
--- a/base/modules/serial/psb_c_base_vect_mod.F90
+++ b/base/modules/serial/psb_c_base_vect_mod.F90
@@ -1155,10 +1155,17 @@ contains
     complex(psb_spk_), intent (in)       :: alpha, beta, gamma, delta
     integer(psb_ipk_), intent(out)              :: info
 
-    if (x%is_dev()) call x%sync()
-
-    call y%axpby(m,alpha,x,beta,info)
-    call z%axpby(m,gamma,y,delta,info)
+    if (.false.) then 
+      if (x%is_dev()) call x%sync()
+      
+      call y%axpby(m,alpha,x,beta,info)
+      call z%axpby(m,gamma,y,delta,info)
+    else
+      if (x%is_dev().and.(alpha/=czero))) call x%sync()
+      if (y%is_dev().and.(beta/=czero))   call y%sync()
+      if (z%is_dev().and.(delta/=czero))  call z%sync()
+      call psi_cabgdxyz(m,alpha, beta, gamma,delta,x%v, y%v, z%v, info)
+    end if
     
   end subroutine c_base_abgdxyz
 
diff --git a/base/modules/serial/psb_c_vect_mod.F90 b/base/modules/serial/psb_c_vect_mod.F90
index 8b2941ff..2eebb0da 100644
--- a/base/modules/serial/psb_c_vect_mod.F90
+++ b/base/modules/serial/psb_c_vect_mod.F90
@@ -1152,7 +1152,7 @@ contains
     end if
 
   end function c_vect_nrm2_weight
-
+ 
   function c_vect_nrm2_weight_mask(n,x,w,id,info,aux) result(res)
     use psi_serial_mod
     implicit none
diff --git a/base/modules/serial/psb_d_base_vect_mod.F90 b/base/modules/serial/psb_d_base_vect_mod.F90
index 29a2ccd8..59b43fce 100644
--- a/base/modules/serial/psb_d_base_vect_mod.F90
+++ b/base/modules/serial/psb_d_base_vect_mod.F90
@@ -1162,10 +1162,17 @@ contains
     real(psb_dpk_), intent (in)       :: alpha, beta, gamma, delta
     integer(psb_ipk_), intent(out)              :: info
 
-    if (x%is_dev()) call x%sync()
-
-    call y%axpby(m,alpha,x,beta,info)
-    call z%axpby(m,gamma,y,delta,info)
+    if (.false.) then 
+      if (x%is_dev()) call x%sync()
+      
+      call y%axpby(m,alpha,x,beta,info)
+      call z%axpby(m,gamma,y,delta,info)
+    else
+      if (x%is_dev().and.(alpha/=dzero))) call x%sync()
+      if (y%is_dev().and.(beta/=dzero))   call y%sync()
+      if (z%is_dev().and.(delta/=dzero))  call z%sync()
+      call psi_dabgdxyz(m,alpha, beta, gamma,delta,x%v, y%v, z%v, info)
+    end if
     
   end subroutine d_base_abgdxyz
 
diff --git a/base/modules/serial/psb_d_vect_mod.F90 b/base/modules/serial/psb_d_vect_mod.F90
index ef75be87..bbb966ed 100644
--- a/base/modules/serial/psb_d_vect_mod.F90
+++ b/base/modules/serial/psb_d_vect_mod.F90
@@ -1159,7 +1159,7 @@ contains
     end if
 
   end function d_vect_nrm2_weight
-
+ 
   function d_vect_nrm2_weight_mask(n,x,w,id,info,aux) result(res)
     use psi_serial_mod
     implicit none
diff --git a/base/modules/serial/psb_s_base_vect_mod.F90 b/base/modules/serial/psb_s_base_vect_mod.F90
index 61ae27d2..dee48ca5 100644
--- a/base/modules/serial/psb_s_base_vect_mod.F90
+++ b/base/modules/serial/psb_s_base_vect_mod.F90
@@ -1162,10 +1162,17 @@ contains
     real(psb_spk_), intent (in)       :: alpha, beta, gamma, delta
     integer(psb_ipk_), intent(out)              :: info
 
-    if (x%is_dev()) call x%sync()
-
-    call y%axpby(m,alpha,x,beta,info)
-    call z%axpby(m,gamma,y,delta,info)
+    if (.false.) then 
+      if (x%is_dev()) call x%sync()
+      
+      call y%axpby(m,alpha,x,beta,info)
+      call z%axpby(m,gamma,y,delta,info)
+    else
+      if (x%is_dev().and.(alpha/=szero))) call x%sync()
+      if (y%is_dev().and.(beta/=szero))   call y%sync()
+      if (z%is_dev().and.(delta/=szero))  call z%sync()
+      call psi_sabgdxyz(m,alpha, beta, gamma,delta,x%v, y%v, z%v, info)
+    end if
     
   end subroutine s_base_abgdxyz
 
diff --git a/base/modules/serial/psb_s_vect_mod.F90 b/base/modules/serial/psb_s_vect_mod.F90
index 34479856..0ffd199f 100644
--- a/base/modules/serial/psb_s_vect_mod.F90
+++ b/base/modules/serial/psb_s_vect_mod.F90
@@ -1159,7 +1159,7 @@ contains
     end if
 
   end function s_vect_nrm2_weight
-
+ 
   function s_vect_nrm2_weight_mask(n,x,w,id,info,aux) result(res)
     use psi_serial_mod
     implicit none
diff --git a/base/modules/serial/psb_z_base_vect_mod.F90 b/base/modules/serial/psb_z_base_vect_mod.F90
index 53f3ea8e..0ab2f945 100644
--- a/base/modules/serial/psb_z_base_vect_mod.F90
+++ b/base/modules/serial/psb_z_base_vect_mod.F90
@@ -1155,10 +1155,17 @@ contains
     complex(psb_dpk_), intent (in)       :: alpha, beta, gamma, delta
     integer(psb_ipk_), intent(out)              :: info
 
-    if (x%is_dev()) call x%sync()
-
-    call y%axpby(m,alpha,x,beta,info)
-    call z%axpby(m,gamma,y,delta,info)
+    if (.false.) then 
+      if (x%is_dev()) call x%sync()
+      
+      call y%axpby(m,alpha,x,beta,info)
+      call z%axpby(m,gamma,y,delta,info)
+    else
+      if (x%is_dev().and.(alpha/=zzero))) call x%sync()
+      if (y%is_dev().and.(beta/=zzero))   call y%sync()
+      if (z%is_dev().and.(delta/=zzero))  call z%sync()
+      call psi_zabgdxyz(m,alpha, beta, gamma,delta,x%v, y%v, z%v, info)
+    end if
     
   end subroutine z_base_abgdxyz
 
diff --git a/base/modules/serial/psb_z_vect_mod.F90 b/base/modules/serial/psb_z_vect_mod.F90
index 54ddfebe..1ea1fd4a 100644
--- a/base/modules/serial/psb_z_vect_mod.F90
+++ b/base/modules/serial/psb_z_vect_mod.F90
@@ -1152,7 +1152,7 @@ contains
     end if
 
   end function z_vect_nrm2_weight
-
+ 
   function z_vect_nrm2_weight_mask(n,x,w,id,info,aux) result(res)
     use psi_serial_mod
     implicit none
diff --git a/base/serial/psi_c_serial_impl.F90 b/base/serial/psi_c_serial_impl.F90
index 129e8484..557220e5 100644
--- a/base/serial/psi_c_serial_impl.F90
+++ b/base/serial/psi_c_serial_impl.F90
@@ -1616,7 +1616,7 @@ subroutine psi_cabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
     call fcpsb_errpush(info,name,int_err)
     goto 9999
   endif
-
+ 
   if (beta == czero) then
     if (gamma == czero) then
       if (alpha == czero) then
@@ -1773,7 +1773,7 @@ subroutine psi_cabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
           end do
           
         else if (delta /= czero) then
-          !  a n b n g n d 0
+          !  a n b n g n d n
           !$omp parallel do private(i)
           do i=1,m
             y(i) = alpha*x(i)+beta*y(i)
diff --git a/base/serial/psi_d_serial_impl.F90 b/base/serial/psi_d_serial_impl.F90
index bd0c82df..d423b401 100644
--- a/base/serial/psi_d_serial_impl.F90
+++ b/base/serial/psi_d_serial_impl.F90
@@ -1616,7 +1616,7 @@ subroutine psi_dabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
     call fcpsb_errpush(info,name,int_err)
     goto 9999
   endif
-
+ 
   if (beta == dzero) then
     if (gamma == dzero) then
       if (alpha == dzero) then
@@ -1773,7 +1773,7 @@ subroutine psi_dabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
           end do
           
         else if (delta /= dzero) then
-          !  a n b n g n d 0
+          !  a n b n g n d n
           !$omp parallel do private(i)
           do i=1,m
             y(i) = alpha*x(i)+beta*y(i)
diff --git a/base/serial/psi_e_serial_impl.F90 b/base/serial/psi_e_serial_impl.F90
index 8b17aeb8..c7977c35 100644
--- a/base/serial/psi_e_serial_impl.F90
+++ b/base/serial/psi_e_serial_impl.F90
@@ -1616,7 +1616,7 @@ subroutine psi_eabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
     call fcpsb_errpush(info,name,int_err)
     goto 9999
   endif
-
+ 
   if (beta == ezero) then
     if (gamma == ezero) then
       if (alpha == ezero) then
@@ -1773,7 +1773,7 @@ subroutine psi_eabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
           end do
           
         else if (delta /= ezero) then
-          !  a n b n g n d 0
+          !  a n b n g n d n
           !$omp parallel do private(i)
           do i=1,m
             y(i) = alpha*x(i)+beta*y(i)
diff --git a/base/serial/psi_i2_serial_impl.F90 b/base/serial/psi_i2_serial_impl.F90
index 9a2c36c6..ce4aff80 100644
--- a/base/serial/psi_i2_serial_impl.F90
+++ b/base/serial/psi_i2_serial_impl.F90
@@ -1616,7 +1616,7 @@ subroutine psi_i2abgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
     call fcpsb_errpush(info,name,int_err)
     goto 9999
   endif
-
+ 
   if (beta == i2zero) then
     if (gamma == i2zero) then
       if (alpha == i2zero) then
@@ -1773,7 +1773,7 @@ subroutine psi_i2abgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
           end do
           
         else if (delta /= i2zero) then
-          !  a n b n g n d 0
+          !  a n b n g n d n
           !$omp parallel do private(i)
           do i=1,m
             y(i) = alpha*x(i)+beta*y(i)
diff --git a/base/serial/psi_m_serial_impl.F90 b/base/serial/psi_m_serial_impl.F90
index dd114a45..8d9d19f4 100644
--- a/base/serial/psi_m_serial_impl.F90
+++ b/base/serial/psi_m_serial_impl.F90
@@ -1616,7 +1616,7 @@ subroutine psi_mabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
     call fcpsb_errpush(info,name,int_err)
     goto 9999
   endif
-
+ 
   if (beta == mzero) then
     if (gamma == mzero) then
       if (alpha == mzero) then
@@ -1773,7 +1773,7 @@ subroutine psi_mabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
           end do
           
         else if (delta /= mzero) then
-          !  a n b n g n d 0
+          !  a n b n g n d n
           !$omp parallel do private(i)
           do i=1,m
             y(i) = alpha*x(i)+beta*y(i)
diff --git a/base/serial/psi_s_serial_impl.F90 b/base/serial/psi_s_serial_impl.F90
index 8e2dda0f..df251b27 100644
--- a/base/serial/psi_s_serial_impl.F90
+++ b/base/serial/psi_s_serial_impl.F90
@@ -1616,7 +1616,7 @@ subroutine psi_sabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
     call fcpsb_errpush(info,name,int_err)
     goto 9999
   endif
-
+ 
   if (beta == szero) then
     if (gamma == szero) then
       if (alpha == szero) then
@@ -1773,7 +1773,7 @@ subroutine psi_sabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
           end do
           
         else if (delta /= szero) then
-          !  a n b n g n d 0
+          !  a n b n g n d n
           !$omp parallel do private(i)
           do i=1,m
             y(i) = alpha*x(i)+beta*y(i)
diff --git a/base/serial/psi_z_serial_impl.F90 b/base/serial/psi_z_serial_impl.F90
index c6a7e01d..44ea5ae7 100644
--- a/base/serial/psi_z_serial_impl.F90
+++ b/base/serial/psi_z_serial_impl.F90
@@ -1616,7 +1616,7 @@ subroutine psi_zabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
     call fcpsb_errpush(info,name,int_err)
     goto 9999
   endif
-
+ 
   if (beta == zzero) then
     if (gamma == zzero) then
       if (alpha == zzero) then
@@ -1773,7 +1773,7 @@ subroutine psi_zabgdxyz(m,alpha, beta, gamma,delta,x, y, z, info)
           end do
           
         else if (delta /= zzero) then
-          !  a n b n g n d 0
+          !  a n b n g n d n
           !$omp parallel do private(i)
           do i=1,m
             y(i) = alpha*x(i)+beta*y(i)