spptrs

NAME

spptrs - solve a system of linear equations A*X = B with a symmetric positive definite matrix A in packed storage using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPPTRF

SYNOPSIS

  SUBROUTINE SPPTRS( UPLO, N, NRHS, A, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER N, NRHS, LDB, INFO
  REAL A(*), B(LDB,*)
 
  SUBROUTINE SPPTRS_64( UPLO, N, NRHS, A, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER*8 N, NRHS, LDB, INFO
  REAL A(*), B(LDB,*)

F95 INTERFACE

  SUBROUTINE PPTRS( UPLO, N, [NRHS], A, B, [LDB], [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER :: N, NRHS, LDB, INFO
  REAL, DIMENSION(:) :: A
  REAL, DIMENSION(:,:) :: B
 
  SUBROUTINE PPTRS_64( UPLO, N, [NRHS], A, B, [LDB], [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER(8) :: N, NRHS, LDB, INFO
  REAL, DIMENSION(:) :: A
  REAL, DIMENSION(:,:) :: B

C INTERFACE

#include <sunperf.h>

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

void spptrs_64(char uplo, long n, long nrhs, float *a, float *b, long ldb, long *info);

PURPOSE

spptrs solves a system of linear equations A*X = B with a symmetric positive definite matrix A in packed storage using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPPTRF.

ARGUMENTS

* UPLO (input)
* N (input): The order of the matrix A. N >= 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, packed columnwise in a linear array. The j-th column of U or L is stored in the array A as follows: if UPLO = 'U', A(i + (j-1)*j/2) = U(i,j) for 1<=i<=j; if UPLO = 'L', A(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
* 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)