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*DECK ALLUS
SUBROUTINE ALLUS(L4,MU1,IMA,ASS,F)
*
*-----------------------------------------------------------------------
*
*Purpose:
* solution of a linear system where the coefficient matrix have been
* factorized by a preceding call to ALLUF.
*
*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.
* IMA position of the first non-zero column element in vector ASS.
* ASS LU factors of the coefficient matrix in compressed diagonal
* storage mode. DIMENSION ASS(IMA(L4))
* F right-hand side of the linear system.
*
*Parameters: output
* F solution of the linear system.
*
*-----------------------------------------------------------------------
*
*----
* SUBROUTINE ARGUMENTS
*----
INTEGER L4,MU1(L4),IMA(L4)
REAL ASS(*),F(L4)
*
F(1)=F(1)/ASS(MU1(1))
DO 20 I=2,L4
K1=IMA(I-1)+1
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
F(I)=-T/ASS(MU1(I))
20 CONTINUE
*
DO 40 I=L4,2,-1
K1=IMA(I)
K2=MU1(I)
KJ=I-K1+K2
T=-F(I)
DO 30 K=K1,K2+1,-1
F(KJ)=F(KJ)+ASS(K)*T
KJ=KJ+1
30 CONTINUE
40 CONTINUE
RETURN
END
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