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360 lines
9.0 KiB
Fortran
360 lines
9.0 KiB
Fortran
!!$
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!!$ Parallel Sparse BLAS version 3.0
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!!$ (C) Copyright 2006, 2007, 2008, 2009, 2010, 2012
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!!$ Salvatore Filippone University of Rome Tor Vergata
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!!$ Alfredo Buttari CNRS-IRIT, Toulouse
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!!$
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!!$ Redistribution and use in source and binary forms, with or without
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!!$ modification, are permitted provided that the following conditions
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!!$ are met:
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!!$ 1. Redistributions of source code must retain the above copyright
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!!$ notice, this list of conditions and the following disclaimer.
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!!$ 2. Redistributions in binary form must reproduce the above copyright
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!!$ notice, this list of conditions, and the following disclaimer in the
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!!$ documentation and/or other materials provided with the distribution.
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!!$ 3. The name of the PSBLAS group or the names of its contributors may
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!!$ not be used to endorse or promote products derived from this
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!!$ software without specific written permission.
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!!$
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!!$ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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!!$ ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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!!$ TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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!!$ PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS
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!!$ BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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!!$ CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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!!$ SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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!!$ INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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!!$ CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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!!$ ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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!!$ POSSIBILITY OF SUCH DAMAGE.
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!!$
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!!$
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subroutine ssr(n,x,dir)
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use psb_serial_mod
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implicit none
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!
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! Quicksort.
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! Adapted from a number of sources, including Don Knuth's TAOCP.
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!
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! .. Scalar Arguments ..
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integer(psb_ipk_), intent(in) :: n, dir
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real(psb_spk_) :: x(n)
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! ..
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! .. Local Scalars ..
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real(psb_spk_) :: piv, xt, xk
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integer(psb_ipk_) :: i, j, ilx, iux, istp, lpiv
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integer(psb_ipk_) :: n1, n2
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integer(psb_ipk_), parameter :: maxstack=64,nparms=3,ithrs=16
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integer(psb_ipk_) :: istack(nparms,maxstack)
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! ..
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!
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! small inputs will only get through insertion sort.
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!
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select case(dir)
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case(psb_sort_up_)
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if (n > ithrs) then
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!
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! Init stack pointer
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!
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istp = 1
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istack(1,istp) = 1
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istack(2,istp) = n
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do
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if (istp <= 0) exit
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ilx = istack(1,istp)
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iux = istack(2,istp)
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istp = istp - 1
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!
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! Choose a pivot with median-of-three heuristics, leave it
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! in the LPIV location
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!
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i = ilx
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j = iux
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lpiv = (i+j)/2
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piv = x(lpiv)
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if (piv < x(i)) then
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xt = x(i)
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x(i) = x(lpiv)
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x(lpiv) = xt
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piv = x(lpiv)
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endif
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if (piv > x(j)) then
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xt = x(j)
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x(j) = x(lpiv)
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x(lpiv) = xt
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piv = x(lpiv)
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endif
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if (piv < x(i)) then
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xt = x(i)
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x(i) = x(lpiv)
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x(lpiv) = xt
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piv = x(lpiv)
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endif
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!
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! now piv is correct; place it into first location
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xt = x(i)
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x(i) = x(lpiv)
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x(lpiv) = xt
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i = ilx - 1
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j = iux + 1
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outer_up: do
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in_up1: do
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i = i + 1
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xk = x(i)
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if (xk >= piv) exit in_up1
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end do in_up1
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!
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! Ensure finite termination for next loop
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!
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xt = xk
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x(i) = piv
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in_up2:do
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j = j - 1
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xk = x(j)
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if (xk <= piv) exit in_up2
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end do in_up2
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x(i) = xt
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if (j > i) then
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xt = x(i)
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x(i) = x(j)
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x(j) = xt
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else
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exit outer_up
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end if
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end do outer_up
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if (i == ilx) then
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if (x(i) /= piv) then
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call psb_errpush(psb_err_internal_error_,r_name='ssr',a_err='impossible pivot condition')
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call psb_error()
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endif
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i = i + 1
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endif
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n1 = (i-1)-ilx+1
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n2 = iux-(i)+1
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if (n1 > n2) then
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if (n1 > ithrs) then
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istp = istp + 1
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istack(1,istp) = ilx
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istack(2,istp) = i-1
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else
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call sisr_up(n1,x(ilx:i-1))
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endif
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if (n2 > ithrs) then
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istp = istp + 1
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istack(1,istp) = i
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istack(2,istp) = iux
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else
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call sisr_up(n2,x(i:iux))
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endif
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else
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if (n2 > ithrs) then
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istp = istp + 1
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istack(1,istp) = i
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istack(2,istp) = iux
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else
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call sisr_up(n2,x(i:iux))
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endif
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if (n1 > ithrs) then
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istp = istp + 1
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istack(1,istp) = ilx
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istack(2,istp) = i-1
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else
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call sisr_up(n1,x(ilx:i-1))
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endif
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endif
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enddo
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else
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call sisr_up(n,x)
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endif
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case(psb_sort_down_)
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if (n > ithrs) then
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!
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! Init stack pointer
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!
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istp = 1
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istack(1,istp) = 1
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istack(2,istp) = n
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do
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if (istp <= 0) exit
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ilx = istack(1,istp)
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iux = istack(2,istp)
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istp = istp - 1
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!
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! Choose a pivot with median-of-three heuristics, leave it
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! in the LPIV location
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!
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i = ilx
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j = iux
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lpiv = (i+j)/2
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piv = x(lpiv)
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if (piv > x(i)) then
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xt = x(i)
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x(i) = x(lpiv)
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x(lpiv) = xt
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piv = x(lpiv)
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endif
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if (piv < x(j)) then
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xt = x(j)
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x(j) = x(lpiv)
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x(lpiv) = xt
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piv = x(lpiv)
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endif
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if (piv > x(i)) then
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xt = x(i)
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x(i) = x(lpiv)
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x(lpiv) = xt
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piv = x(lpiv)
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endif
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!
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! now piv is correct; place it into first location
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xt = x(i)
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x(i) = x(lpiv)
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x(lpiv) = xt
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i = ilx - 1
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j = iux + 1
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outer_dw: do
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in_dw1: do
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i = i + 1
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xk = x(i)
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if (xk <= piv) exit in_dw1
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end do in_dw1
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!
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! Ensure finite termination for next loop
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!
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xt = xk
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x(i) = piv
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in_dw2:do
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j = j - 1
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xk = x(j)
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if (xk >= piv) exit in_dw2
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end do in_dw2
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x(i) = xt
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if (j > i) then
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xt = x(i)
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x(i) = x(j)
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x(j) = xt
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else
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exit outer_dw
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end if
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end do outer_dw
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if (i == ilx) then
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if (x(i) /= piv) then
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call psb_errpush(psb_err_internal_error_,r_name='ssr',a_err='impossible pivot condition')
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call psb_error()
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endif
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i = i + 1
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endif
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n1 = (i-1)-ilx+1
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n2 = iux-(i)+1
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if (n1 > n2) then
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if (n1 > ithrs) then
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istp = istp + 1
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istack(1,istp) = ilx
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istack(2,istp) = i-1
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else
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call sisr_dw(n1,x(ilx:i-1))
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endif
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if (n2 > ithrs) then
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istp = istp + 1
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istack(1,istp) = i
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istack(2,istp) = iux
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else
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call sisr_dw(n2,x(i:iux))
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endif
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else
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if (n2 > ithrs) then
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istp = istp + 1
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istack(1,istp) = i
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istack(2,istp) = iux
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else
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call sisr_dw(n2,x(i:iux))
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endif
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if (n1 > ithrs) then
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istp = istp + 1
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istack(1,istp) = ilx
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istack(2,istp) = i-1
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else
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call sisr_dw(n1,x(ilx:i-1))
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endif
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endif
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enddo
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else
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call sisr_dw(n,x)
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endif
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case default
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call psb_errpush(psb_err_internal_error_,r_name='ssr',a_err='wrong dir')
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call psb_error()
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end select
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return
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contains
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subroutine sisr_up(n,x)
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implicit none
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integer(psb_ipk_) :: n
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real(psb_spk_) :: x(n)
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integer(psb_ipk_) :: i,j
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real(psb_spk_) :: xx
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do j=n-1,1,-1
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if (x(j+1) < x(j)) then
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xx = x(j)
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i=j+1
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do
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x(i-1) = x(i)
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i = i+1
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if (i>n) exit
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if (x(i) >= xx) exit
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end do
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x(i-1) = xx
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endif
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enddo
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end subroutine sisr_up
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subroutine sisr_dw(n,x)
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implicit none
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integer(psb_ipk_) :: n
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real(psb_spk_) :: x(n)
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integer(psb_ipk_) :: i,j
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real(psb_spk_) :: xx
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do j=n-1,1,-1
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if (x(j+1) > x(j)) then
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xx = x(j)
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i=j+1
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do
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x(i-1) = x(i)
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i = i+1
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if (i>n) exit
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if (x(i) <= xx) exit
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end do
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x(i-1) = xx
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endif
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enddo
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end subroutine sisr_dw
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end subroutine ssr
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