dsisl.f
SUBROUTINE DSISL (A, LDA, N, KPVT, B)
C***BEGIN PROLOGUE DSISL
C***PURPOSE Solve a real symmetric system using the factors obtained
C from SSIFA.
C***LIBRARY SLATEC (LINPACK)
C***CATEGORY D2B1A
C***TYPE DOUBLE PRECISION (SSISL-S, DSISL-D, CHISL-C, CSISL-C)
C***KEYWORDS LINEAR ALGEBRA, LINPACK, MATRIX, SOLVE, SYMMETRIC
C***AUTHOR Bunch, J., (UCSD)
C***DESCRIPTION
C
C DSISL solves the double precision symmetric system
C A * X = B
C using the factors computed by DSIFA.
C
C On Entry
C
C A DOUBLE PRECISION(LDA,N)
C the output from DSIFA.
C
C LDA INTEGER
C the leading dimension of the array A .
C
C N INTEGER
C the order of the matrix A .
C
C KPVT INTEGER(N)
C the pivot vector from DSIFA.
C
C B DOUBLE PRECISION(N)
C the right hand side vector.
C
C On Return
C
C B the solution vector X .
C
C Error Condition
C
C A division by zero may occur if DSICO has set RCOND .EQ. 0.0
C or DSIFA has set INFO .NE. 0 .
C
C To compute INVERSE(A) * C where C is a matrix
C with P columns
C CALL DSIFA(A,LDA,N,KPVT,INFO)
C IF (INFO .NE. 0) GO TO ...
C DO 10 J = 1, P
C CALL DSISL(A,LDA,N,KPVT,C(1,J))
C 10 CONTINUE
C
C***REFERENCES J. J. Dongarra, J. R. Bunch, C. B. Moler, and G. W.
C Stewart, LINPACK Users' Guide, SIAM, 1979.
C***ROUTINES CALLED DAXPY, DDOT
C***REVISION HISTORY (YYMMDD)
C 780814 DATE WRITTEN
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890831 Modified array declarations. (WRB)
C 891107 Modified routine equivalence list. (WRB)
C 891107 REVISION DATE from Version 3.2
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900326 Removed duplicate information from DESCRIPTION section.
C (WRB)
C 920501 Reformatted the REFERENCES section. (WRB)
C***END PROLOGUE DSISL