spotrs(3)

NAME

SPOTRS - solve a system of linear equations A*X = B with a

symmetric positive definite matrix A using the Cholesky factor

ization A = U**T*U or A = L*L**T computed by SPOTRF

SYNOPSIS

SUBROUTINE SPOTRS( UPLO, N, NRHS, A, LDA, B, LDB, INFO )
    CHARACTER      UPLO
    INTEGER        INFO, LDA, LDB, N, NRHS
    REAL           A( LDA, * ), B( LDB, * )

PURPOSE

SPOTRS solves a system of linear equations A*X = B with a

symmetric positive definite matrix A using the Cholesky factor

ization A = U**T*U or A = L*L**T computed by SPOTRF.

ARGUMENTS

UPLO (input) CHARACTER*1

= 'U': Upper triangle of A is stored;
= 'L': Lower triangle of A is stored.

N (input) INTEGER

The order of the matrix A. N >= 0.

NRHS (input) INTEGER

The number of right hand sides, i.e., the number

of columns of the matrix B. NRHS >= 0.

A (input) REAL array, dimension (LDA,N)

The triangular factor U or L from the Cholesky

factorization A = U**T*U or A = L*L**T, as computed by SPOTRF.

LDA (input) INTEGER

The leading dimension of the array A. LDA >=

max(1,N).

B (input/output) REAL array, dimension (LDB,NRHS)

On entry, the right hand side matrix B. On exit,

the solution matrix X.

LDB (input) INTEGER

The leading dimension of the array B. LDB >=

max(1,N).

INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = -i, the i-th argument had an ille

gal value

LAPACK version 3.0 15 June 2000

SPOTRS(3)