SPOTRS (3lapack)

solve a system of linear equations A*X = B with a symmetric positive definite matrix A using the Cholesky factorization 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 factorization 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 illegal value