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# zgetrs

```
NAME
ZGETRS - solve a system of linear equations  A * X = B, A**T
* X = B, or A**H * X = B with a general N-by-N matrix A
using the LU factorization computed by ZGETRF

SYNOPSIS
SUBROUTINE ZGETRS( TRANS, N, NRHS, A, LDA, IPIV, B, LDB,
INFO )

CHARACTER      TRANS

INTEGER        INFO, LDA, LDB, N, NRHS

INTEGER        IPIV( * )

COMPLEX*16     A( LDA, * ), B( LDB, * )

PURPOSE
ZGETRS solves a system of linear equations
A * X = B,  A**T * X = B,  or  A**H * X = B with a gen-
eral N-by-N matrix A using the LU factorization computed by
ZGETRF.

ARGUMENTS
TRANS   (input) CHARACTER*1
Specifies the form of the system of equations:
= 'N':  A * X = B     (No transpose)
= 'T':  A**T * X = B  (Transpose)
= 'C':  A**H * X = B  (Conjugate transpose)

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) COMPLEX*16 array, dimension (LDA,N)
The factors L and U from the factorization A = P*L*U
as computed by ZGETRF.

LDA     (input) INTEGER
The leading dimension of the array A.  LDA >=
max(1,N).

IPIV    (input) INTEGER array, dimension (N)
The pivot indices from ZGETRF; for 1<=i<=N, row i of
the matrix was interchanged with row IPIV(i).

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
```