sposv

NAME

sposv - compute the solution to a real system of linear equations A * X = B,

SYNOPSIS

  SUBROUTINE SPOSV( UPLO, N, NRHS, A, LDA, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER N, NRHS, LDA, LDB, INFO
  REAL A(LDA,*), B(LDB,*)
 
  SUBROUTINE SPOSV_64( UPLO, N, NRHS, A, LDA, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER*8 N, NRHS, LDA, LDB, INFO
  REAL A(LDA,*), B(LDB,*)

F95 INTERFACE

  SUBROUTINE POSV( UPLO, [N], [NRHS], A, [LDA], B, [LDB], [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER :: N, NRHS, LDA, LDB, INFO
  REAL, DIMENSION(:,:) :: A, B
 
  SUBROUTINE POSV_64( UPLO, [N], [NRHS], A, [LDA], B, [LDB], [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER(8) :: N, NRHS, LDA, LDB, INFO
  REAL, DIMENSION(:,:) :: A, B

C INTERFACE

#include <sunperf.h>

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

void sposv_64(char uplo, long n, long nrhs, float *a, long lda, float *b, long ldb, long *info);

PURPOSE

sposv computes the solution to a real system of linear equations A * X = B, where A is an N-by-N symmetric positive definite matrix and X and B are N-by-NRHS matrices.

The Cholesky decomposition is used to factor A as

   A = U**T* U,  if UPLO = 'U', or
   A = L * L**T,  if UPLO = 'L',

where U is an upper triangular matrix and L is a lower triangular matrix. The factored form of A is then used to solve the system of equations A * X = B.

ARGUMENTS

* UPLO (input)

* N (input)

The number of linear equations, i.e., 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/output)

On entry, the symmetric matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced.

On exit, if INFO = 0, the factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T.

* LDA (input)

The leading dimension of the array A. LDA >= max(1,N).

* B (input/output)

On entry, the N-by-NRHS right hand side matrix B. On exit, if INFO = 0, the N-by-NRHS solution matrix X.

* LDB (input)

The leading dimension of the array B. LDB >= max(1,N).

* INFO (output)