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man pages->IRIX man pages -> complib/zlagtm (3)
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### Contents

```
ZLAGTM(3F)							    ZLAGTM(3F)

```

### NAME[Toc][Back]

```     ZLAGTM - perform a	matrix-vector product of the form   B := alpha * A * X
+ beta * B	 where A is a tridiagonal matrix of order N, B and X are N by
NRHS matrices, and	alpha and beta are real	scalars, each of which may be
0., 1., or	-1
```

### SYNOPSIS[Toc][Back]

```     SUBROUTINE	ZLAGTM(	TRANS, N, NRHS,	ALPHA, DL, D, DU, X, LDX, BETA,	B, LDB
)

CHARACTER	TRANS

INTEGER	LDB, LDX, N, NRHS

DOUBLE		PRECISION ALPHA, BETA

COMPLEX*16	B( LDB,	* ), D(	* ), DL( * ), DU( * ), X( LDX, * )
```

### PURPOSE[Toc][Back]

```     ZLAGTM performs a matrix-vector product of	the form

```

### ARGUMENTS[Toc][Back]

```     TRANS   (input) CHARACTER
Specifies the operation applied to	A.  = 'N':  No transpose, B :=
alpha * A * X + beta * B
= 'T':  Transpose,	   B :=	alpha *	A**T * X + beta	* B
= 'C':  Conjugate transpose, B := alpha * A**H * X	+ beta * B

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 matrices X and	B.

ALPHA   (input) DOUBLE PRECISION
The scalar	alpha.	ALPHA must be 0., 1., or -1.; otherwise, it is
assumed to	be 0.

DL	     (input) COMPLEX*16	array, dimension (N-1)
The (n-1) sub-diagonal elements of	T.

D	     (input) COMPLEX*16	array, dimension (N)
The diagonal elements of T.

DU	     (input) COMPLEX*16	array, dimension (N-1)
The (n-1) super-diagonal elements of T.

X	     (input) COMPLEX*16	array, dimension (LDX,NRHS)
The N by NRHS matrix X.  LDX     (input) INTEGER The leading
dimension of the array X.	LDX >= max(N,1).

Page 1

ZLAGTM(3F)							    ZLAGTM(3F)

BETA    (input) DOUBLE PRECISION
The scalar	beta.  BETA must be 0.,	1., or -1.; otherwise, it is
assumed to	be 1.

B	     (input/output) 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     (input) INTEGER
The leading dimension of the array	B.  LDB	>= max(N,1).
ZLAGTM(3F)							    ZLAGTM(3F)

```

### NAME[Toc][Back]

```     ZLAGTM - perform a	matrix-vector product of the form   B := alpha * A * X
+ beta * B	 where A is a tridiagonal matrix of order N, B and X are N by
NRHS matrices, and	alpha and beta are real	scalars, each of which may be
0., 1., or	-1
```

### SYNOPSIS[Toc][Back]

```     SUBROUTINE	ZLAGTM(	TRANS, N, NRHS,	ALPHA, DL, D, DU, X, LDX, BETA,	B, LDB
)

CHARACTER	TRANS

INTEGER	LDB, LDX, N, NRHS

DOUBLE		PRECISION ALPHA, BETA

COMPLEX*16	B( LDB,	* ), D(	* ), DL( * ), DU( * ), X( LDX, * )
```

### PURPOSE[Toc][Back]

```     ZLAGTM performs a matrix-vector product of	the form

```

### ARGUMENTS[Toc][Back]

```     TRANS   (input) CHARACTER
Specifies the operation applied to	A.  = 'N':  No transpose, B :=
alpha * A * X + beta * B
= 'T':  Transpose,	   B :=	alpha *	A**T * X + beta	* B
= 'C':  Conjugate transpose, B := alpha * A**H * X	+ beta * B

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 matrices X and	B.

ALPHA   (input) DOUBLE PRECISION
The scalar	alpha.	ALPHA must be 0., 1., or -1.; otherwise, it is
assumed to	be 0.

DL	     (input) COMPLEX*16	array, dimension (N-1)
The (n-1) sub-diagonal elements of	T.

D	     (input) COMPLEX*16	array, dimension (N)
The diagonal elements of T.

DU	     (input) COMPLEX*16	array, dimension (N-1)
The (n-1) super-diagonal elements of T.

X	     (input) COMPLEX*16	array, dimension (LDX,NRHS)
The N by NRHS matrix X.  LDX     (input) INTEGER The leading
dimension of the array X.	LDX >= max(N,1).

Page 1

ZLAGTM(3F)							    ZLAGTM(3F)

BETA    (input) DOUBLE PRECISION
The scalar	beta.  BETA must be 0.,	1., or -1.; otherwise, it is
assumed to	be 1.

B	     (input/output) 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     (input) INTEGER
The leading dimension of the array	B.  LDB	>= max(N,1).

PPPPaaaaggggeeee 2222```
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