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zgtsv.f -

# SYNOPSIS

## Functions/Subroutines

subroutine zgtsv (N, NRHS, DL, D, DU, B, LDB, INFO)

ZGTSV computes the solution to system of linear equations A * X = B for GT matrices

# Function/Subroutine Documentation

## subroutine zgtsv (integerN, integerNRHS, complex*16, dimension( * )DL, complex*16, dimension( * )D, complex*16, dimension( * )DU, complex*16, dimension( ldb, * )B, integerLDB, integerINFO)

ZGTSV computes the solution to system of linear equations A * X = B for GT matrices
Purpose:
``` ZGTSV  solves the equation

A*X = B,

where A is an N-by-N tridiagonal matrix, by Gaussian elimination with
partial pivoting.

Note that the equation  A**T *X = B  may be solved by interchanging the
order of the arguments DU and DL.
```
Parameters:
N
```          N is INTEGER
The order of the matrix A.  N >= 0.
```
NRHS
```          NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrix B.  NRHS >= 0.
```
DL
```          DL is COMPLEX*16 array, dimension (N-1)
On entry, DL must contain the (n-1) subdiagonal elements of
A.
On exit, DL is overwritten by the (n-2) elements of the
second superdiagonal of the upper triangular matrix U from
the LU factorization of A, in DL(1), ..., DL(n-2).
```
D
```          D is COMPLEX*16 array, dimension (N)
On entry, D must contain the diagonal elements of A.
On exit, D is overwritten by the n diagonal elements of U.
```
DU
```          DU is COMPLEX*16 array, dimension (N-1)
On entry, DU must contain the (n-1) superdiagonal elements
of A.
On exit, DU is overwritten by the (n-1) elements of the first
superdiagonal of U.
```
B
```          B is COMPLEX*16 array, dimension (LDB,NRHS)
On entry, the N-by-NRHS right hand side matrix B.
On exit, if INFO = 0, the N-by-NRHS solution matrix X.
```
LDB
```          LDB is INTEGER
The leading dimension of the array B.  LDB >= max(1,N).
```
INFO
```          INFO is INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
> 0:  if INFO = i, U(i,i) is exactly zero, and the solution
has not been computed.  The factorization has not been
completed unless i = N.
```
Author:
Univ. of Tennessee
Univ. of California Berkeley
NAG Ltd.
Date:
September 2012
Definition at line 125 of file zgtsv.f.

# Author

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