# zpttrs.f - Man Page

SRC/zpttrs.f

## Synopsis

### Functions/Subroutines

subroutine zpttrs (uplo, n, nrhs, d, e, b, ldb, info)
ZPTTRS

## Function/Subroutine Documentation

### subroutine zpttrs (character uplo, integer n, integer nrhs, double precision, dimension( * ) d, complex*16, dimension( * ) e, complex*16, dimension( ldb, * ) b, integer ldb, integer info)

ZPTTRS

Purpose:

``` ZPTTRS solves a tridiagonal system of the form
A * X = B
using the factorization A = U**H *D* U or A = L*D*L**H computed by ZPTTRF.
D is a diagonal matrix specified in the vector D, U (or L) is a unit
bidiagonal matrix whose superdiagonal (subdiagonal) is specified in
the vector E, and X and B are N by NRHS matrices.```
Parameters

UPLO

```          UPLO is CHARACTER*1
Specifies the form of the factorization and whether the
vector E is the superdiagonal of the upper bidiagonal factor
U or the subdiagonal of the lower bidiagonal factor L.
= 'U':  A = U**H *D*U, E is the superdiagonal of U
= 'L':  A = L*D*L**H, E is the subdiagonal of L```

N

```          N is INTEGER
The order of the tridiagonal 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.```

D

```          D is DOUBLE PRECISION array, dimension (N)
The n diagonal elements of the diagonal matrix D from the
factorization A = U**H *D*U or A = L*D*L**H.```

E

```          E is COMPLEX*16 array, dimension (N-1)
If UPLO = 'U', the (n-1) superdiagonal elements of the unit
bidiagonal factor U from the factorization A = U**H*D*U.
If UPLO = 'L', the (n-1) subdiagonal elements of the unit
bidiagonal factor L from the factorization A = L*D*L**H.```

B

```          B is COMPLEX*16 array, dimension (LDB,NRHS)
On entry, the right hand side vectors B for the system of
linear equations.
On exit, the solution vectors, 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 = -k, the k-th argument had an illegal value```
Author

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Definition at line 120 of file zpttrs.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page zpttrs(3) is an alias of zpttrs.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK