DPBSL(3)

SYNOPSIS
SUBROUTINE DPBSL (ABD, LDA, N, M, B)

NAME
dpbsl - Solve a real symmetric positive definite band system using the factors computed by DPBCO or DPBFA.

LIBRARY
SLATEC (LINPACK)

CATEGORY
D2B2

TYPE
DOUBLE PRECISION (SPBSL-S, DPBSL-D, CPBSL-C)

KEYWORDS
BANDED, LINEAR ALGEBRA, LINPACK, MATRIX, POSITIVE DEFINITE, SOLVE

AUTHOR
Moler, C. B., (U. of New Mexico)

DESCRIPTION
DPBSL solves the double precision symmetric positive definite band system A*X = B using the factors computed by DPBCO or DPBFA. On Entry ABD DOUBLE PRECISION(LDA, N) the output from DPBCO or DPBFA. LDA INTEGER the leading dimension of the array ABD . N INTEGER the order of the matrix A . M INTEGER the number of diagonals above the main diagonal. B DOUBLE PRECISION(N) the right hand side vector. On Return B the solution vector X . Error Condition A division by zero will occur if the input factor contains a zero on the diagonal. Technically this indicates singularity, but it is usually caused by improper subroutine arguments. It will not occur if the subroutines are called correctly, and INFO .EQ. 0 . To compute INVERSE(A) * C where C is a matrix with P columns CALL DPBCO(ABD,LDA,N,RCOND,Z,INFO) IF (RCOND is too small .OR. INFO .NE. 0) GO TO ... DO 10 J = 1, P CALL DPBSL(ABD,LDA,N,C(1,J)) 10 CONTINUE

REFERENCES
J. J. Dongarra, J. R. Bunch, C. B. Moler, and G. W. Stewart, LINPACK Users' Guide, SIAM, 1979.

ROUTINES CALLED
DAXPY, DDOT

REVISION HISTORY (YYMMDD)
780814 DATE WRITTEN
890531 Changed all specific intrinsics to generic. (WRB)
890831 Modified array declarations. (WRB)
890831 REVISION DATE from Version 3.2
891214 Prologue converted to Version 4.0 format. (BAB)
900326 Removed duplicate information from DESCRIPTION section. (WRB)
920501 Reformatted the REFERENCES section. (WRB)