ZPPTRS (3lapack)

solve a system of linear equations A*X = B with a Hermitian positive definite matrix A in packed storage using the Cholesky factorization A = U**H*U or A = L*L**H computed by ZPPTRF

SYNOPSIS

  SUBROUTINE ZPPTRS( UPLO, N, NRHS, AP, B, LDB, INFO )

      CHARACTER      UPLO

      INTEGER        INFO, LDB, N, NRHS

      COMPLEX*16     AP( * ), B( LDB, * )

PURPOSE

  ZPPTRS solves a system of linear equations A*X = B with a Hermitian
  positive definite matrix A in packed storage using the Cholesky
  factorization A = U**H*U or A = L*L**H computed by ZPPTRF.

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.

  AP      (input) COMPLEX*16 array, dimension (N*(N+1)/2)
          The triangular factor U or L from the Cholesky factorization A =
          U**H*U or A = L*L**H, packed columnwise in a linear array.  The j-
          th column of U or L is stored in the array AP as follows: if UPLO =
          'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j; if UPLO = 'L', AP(i +
          (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.

  B       (input/output) COMPLEX*16 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