---
name: "zlaptm.f"
section: "3"
platform: "linux"
package: "lapack-doc"
version: "3.12.1-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/zlaptm.f"
---

# zlaptm.f(3)

## NAME

TESTING/LIN/zlaptm.f

## SYNOPSIS

### Functions/Subroutines

subroutine **zlaptm** (uplo, n, nrhs, alpha, d, e, x, ldx, beta, b, ldb)\
 **ZLAPTM**

## Function/Subroutine Documentation

### subroutine zlaptm (character uplo, integer n, integer nrhs, double precision alpha, double precision, dimension( \* ) d, complex\*16, dimension( \* ) e, complex\*16, dimension( ldx, \* ) x, integer ldx, double precision beta, complex\*16, dimension( ldb, \* ) b, integer ldb)

**ZLAPTM**

**Purpose:**

```
!>
!> ZLAPTM multiplies an N by NRHS matrix X by a Hermitian tridiagonal
!> matrix A and stores the result in a matrix B.  The operation has the
!> form
!>
!>    B := alpha * A * X + beta * B
!>
!> where alpha may be either 1. or -1. and beta may be 0., 1., or -1.
!>
```

**Parameters**

*UPLO*

```
!>          UPLO is CHARACTER
!>          Specifies whether the superdiagonal or the subdiagonal of the
!>          tridiagonal matrix A is stored.
!>          = 'U':  Upper, E is the superdiagonal of A.
!>          = 'L':  Lower, E is the subdiagonal of A.
!>
```

*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 matrices X and B.
!>
```

*ALPHA*

```
!>          ALPHA is DOUBLE PRECISION
!>          The scalar alpha.  ALPHA must be 1. or -1.; otherwise,
!>          it is assumed to be 0.
!>
```

*D*

```
!>          D is DOUBLE PRECISION array, dimension (N)
!>          The n diagonal elements of the tridiagonal matrix A.
!>
```

*E*

```
!>          E is COMPLEX*16 array, dimension (N-1)
!>          The (n-1) subdiagonal or superdiagonal elements of A.
!>
```

*X*

```
!>          X is COMPLEX*16 array, dimension (LDX,NRHS)
!>          The N by NRHS matrix X.
!>
```

*LDX*

```
!>          LDX is INTEGER
!>          The leading dimension of the array X.  LDX >= max(N,1).
!>
```

*BETA*

```
!>          BETA is DOUBLE PRECISION
!>          The scalar beta.  BETA must be 0., 1., or -1.; otherwise,
!>          it is assumed to be 1.
!>
```

*B*

```
!>          B is COMPLEX*16 array, dimension (LDB,NRHS)
!>          On entry, the N by NRHS matrix B.
!>          On exit, B is overwritten by the matrix expression
!>          B := alpha * A * X + beta * B.
!>
```

*LDB*

```
!>          LDB is INTEGER
!>          The leading dimension of the array B.  LDB >= max(N,1).
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **127** of file **zlaptm.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.