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man pages->IRIX man pages -> libblas/rotmg (3)
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### Contents

```
_ROTMG(3F)							    _ROTMG(3F)

```

### NAME[Toc][Back]

```     drotmg, srotmg - BLAS Level-1. Compute the	elements of a modified Givens
plane rotation.

FORTRAN	SYNOPSIS
subroutine	drotmg(	d1, d2,	x1, y1,	param )
double precision	d1, d2,	x1, y1
double precision	param( 5 )

subroutine	srotmg(	d1, d2,	x1, y1,	param )
real		d1, d2,	x1, y1
real		param( 5 )

```

### DESCRIPTION[Toc][Back]

```     DROTMG and	SROTMG compute the elements of a modified Givens rotation
matrix.

```

### PARAMETERS[Toc][Back]

```     d1	     (input/output)
On	input, this value is the first diagonal	element	of the scaling
matrix D.	On first call to DROTMG	or SROTMG, this	value is
typically 1.0. Subsequent calls typically use the value from the
previous call.
On	output,	this value is the first	diagonal element of the
updated scaling matrix D'.

d2	     (input/output)
On	input, this value is the second	diagonal element of the
scaling matrix D.	On first call to DROTMG	or SROTMG, this	value
is	typically 1.0. Subsequent calls	typically use the value	from
the previous call.
On	output,	this value is the first	diagonal element of the
updated scaling matrix D'.

x1	     (input/output)
On	input, this value is the x-coordinate of the vector used to
define the	angle of rotation before scaling (multiplying by the
matrix D).
On	output,	this value is the x-coordinate of the rotated vector
before scaling (multiplying by the	matrix D').

y1	     (input/output)
On	input, this value is the y-coordinate of the vector used to
define the	angle of rotation before scaling (multiplying by the
matrix D).
On	output,	this value is the y coordinate of the rotated vecttor
before scaling (multiplying by the	matrix D').

Page 1

_ROTMG(3F)							    _ROTMG(3F)

param   (output)
This array	contains rotation matrix information. DROTMG or	SROTMG
set up the	computed elements in param from	inputs d1, d2, x1, and
y1.

```

```     DROTM or SROTM.