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*DECK ALSVDS
SUBROUTINE ALSVDS(U,W,V,M,N,MP,NP,B,X)
*
*-----------------------------------------------------------------------
*
*Purpose:
* linear system solution after singular value decomposition.
*
*Copyright:
* Copyright (C) 1993 Ecole Polytechnique de Montreal
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version
*
*Author(s): A. Hebert
*
*Parameters: input
* U first decomposed matrix.
* W singular values.
* V second decomposed matrix.
* M,N first/second mathematical dimension of matrix A
* MP,NP first/second physical dimension of matrix A
* B RHS vector.
*
*Parameters: output
* X solution vector.
*
*-----------------------------------------------------------------------
*
INTEGER M,MP,N,NP
DOUBLE PRECISION B(MP),U(MP,NP),V(NP,NP),W(NP),X(NP),S
INTEGER I,J,JJ
DOUBLE PRECISION, DIMENSION(:), ALLOCATABLE :: TMP
*
ALLOCATE(TMP(NP))
DO 12 J=1,N
S=0.0D0
IF(W(J).NE.0.0D0)THEN
DO 11 I=1,M
S=S+U(I,J)*B(I)
11 CONTINUE
S=S/W(J)
ENDIF
TMP(J)=S
12 CONTINUE
DO 14 J=1,N
S=0.0D0
DO 13 JJ=1,N
S=S+V(J,JJ)*TMP(JJ)
13 CONTINUE
X(J)=S
14 CONTINUE
DEALLOCATE(TMP)
RETURN
END
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