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*DECK ALLDLS
SUBROUTINE ALLDLS (L4,MU1,ASS,F)
*
*-----------------------------------------------------------------------
*
*Purpose:
* solution of a symmetric linear system where the coefficient matrix
* have been factorized by a preceding call to ALLDLF.
*
*Copyright:
* Copyright (C) 1989 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
* L4 order of the coefficient matrix.
* MU1 position of each diagonal element in vector ASS.
* ASS LDL(T) factors of the coefficient matrix in compressed
* diagonal storage mode. DIMENSION ASS(MU1(L4)-MU1(1)+1)
* F right-hand side of the linear system.
*
*Parameters: output
* F solution of the linear system.
*
*-----------------------------------------------------------------------
*
*----
* SUBROUTINE ARGUMENTS
*----
INTEGER L4,MU1(L4)
REAL ASS(*),F(L4)
*
IF (L4.EQ.1) GO TO 60
K1=MU1(1)+1
DO 20 I=2,L4
K2=MU1(I)
KJ=I-K2+K1
T=-F(I)
DO 10 K=K1,K2-1
T=T+F(KJ)*ASS(K)
KJ=KJ+1
10 CONTINUE
K1=K2+1
F(I)=-T
20 CONTINUE
C
DO 30 I=1,L4
F(I)=F(I)*ASS(MU1(I))
30 CONTINUE
C
K2=MU1(L4)
DO 50 I=L4,2,-1
T=-F(I)
K1=MU1(I-1)+1
KJ=I-K2+K1
DO 40 K=K1,K2-1
F(KJ)=F(KJ)+ASS(K)*T
KJ=KJ+1
40 CONTINUE
K2=K1-1
50 CONTINUE
RETURN
C
60 F(1)=F(1)*ASS(MU1(1))
RETURN
END
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