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# zpptrs

```
NAME
ZPPTRS - 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
Specifies whether the factor stored in A is upper or
lower triangular.  = '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 fac-
torization A = U**H*U or A = L*L**H, packed column-
wise 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
```