SPBSL(3F)
SPBSL - SPBSL solves the real symmetric positive definite band system A*X = B using the factors computed by SPBCO or SPBFA.
As shipped in IRIX 6.5.22. Unchanged since IRIX 6.5.
NAME SPBSL - SPBSL solves the real symmetric positive definite band system A*X = B using the factors computed by SPBCO or SPBFA. SYNOPSYS SUBROUTINE SPBSL(ABD,LDA,N,M,B) DESCRIPTION On Entry ABD REAL(LDA, N) the output from SPBCO or SPBFA. 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 REAL(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 SPBCO(ABD,LDA,N,RCOND,Z,INFO) IF (RCOND is too small .OR. INFO .NE. 0) GO TO ... DO 10 J = 1, P CALL SPBSL(ABD,LDA,N,C(1,J)) 10 CONTINUE LINPACK. This version dated 08/14/78 . Cleve Moler, University of New Mexico, Argonne National Lab. Subroutines and Functions BLAS SAXPY,SDOT Fortran MIN0