spptrs(3P) Sun Performance Library spptrs(3P)NAMEspptrs - solve a system of linear equations A*X = B with a symmetric
positive definite matrix A in packed storage using the Cholesky factor‐
ization 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);
PURPOSEspptrs solves a system of linear equations A*X = B with a symmetric
positive definite matrix A in packed storage using the Cholesky factor‐
ization 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) REAL array, dimension (N*(N+1)/2)
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 solu‐
tion 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
6 Mar 2009 spptrs(3P)
