• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

dpptrs - 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 DPPTRS( UPLO, N, NRHS, A, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER N, NRHS, LDB, INFO
  DOUBLE PRECISION A(*), B(LDB,*)

  SUBROUTINE DPPTRS_64( UPLO, N, NRHS, A, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER*8 N, NRHS, LDB, INFO
  DOUBLE PRECISION A(*), B(LDB,*)

F95 INTERFACE

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

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

C INTERFACE

#include <sunperf.h>

void dpptrs(char uplo, int n, int nrhs, double *a, double *b, int ldb, int *info);

void dpptrs_64(char uplo, long n, long nrhs, double *a, double *b, long ldb, long *info);

PURPOSE

dpptrs 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)
  

   = 'U':  Upper triangle of A is stored;

   = 'L':  Lower triangle of A is stored.

• 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)
  

   = 0:  successful exit

   < 0:  if INFO  = -i, the i-th argument had an illegal value