spbtrs

NAME

spbtrs - solve a system of linear equations A*X = B with a symmetric positive definite band matrix A using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPBTRF

SYNOPSIS

  SUBROUTINE SPBTRS( UPLO, N, NDIAG, NRHS, A, LDA, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER N, NDIAG, NRHS, LDA, LDB, INFO
  REAL A(LDA,*), B(LDB,*)
 
  SUBROUTINE SPBTRS_64( UPLO, N, NDIAG, NRHS, A, LDA, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER*8 N, NDIAG, NRHS, LDA, LDB, INFO
  REAL A(LDA,*), B(LDB,*)

F95 INTERFACE

  SUBROUTINE PBTRS( UPLO, [N], NDIAG, [NRHS], A, [LDA], B, [LDB], 
 *       [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER :: N, NDIAG, NRHS, LDA, LDB, INFO
  REAL, DIMENSION(:,:) :: A, B
 
  SUBROUTINE PBTRS_64( UPLO, [N], NDIAG, [NRHS], A, [LDA], B, [LDB], 
 *       [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER(8) :: N, NDIAG, NRHS, LDA, LDB, INFO
  REAL, DIMENSION(:,:) :: A, B

C INTERFACE

#include <sunperf.h>

void spbtrs(char uplo, int n, int ndiag, int nrhs, float *a, int lda, float *b, int ldb, int *info);

void spbtrs_64(char uplo, long n, long ndiag, long nrhs, float *a, long lda, float *b, long ldb, long *info);

PURPOSE

spbtrs solves a system of linear equations A*X = B with a symmetric positive definite band matrix A using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPBTRF.

ARGUMENTS

* UPLO (input)
* N (input): The order of the matrix A. N >= 0.
* NDIAG (input): The number of superdiagonals of the matrix A if UPLO = 'U', or the number of subdiagonals if UPLO = 'L'. NDIAG >= 0.
* NRHS (input): The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.
* A (input): The triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T of the band matrix A, stored in the first NDIAG+1 rows of the array. The j-th column of U or L is stored in the j-th column of the array A as follows: if UPLO ='U', A(kd+1+i-j,j) = U(i,j) for max(1,j-kd)<=i<=j; if UPLO ='L', A(1+i-j,j) = L(i,j) for j<=i<=min(n,j+kd).
* LDA (input): The leading dimension of the array A. LDA >= NDIAG+1.
* B (input/output): On entry, the right hand side matrix B. On exit, the solution matrix X.
* LDB (input): The leading dimension of the array B. LDB >= max(1,N).
* INFO (output)