slartgp()

subroutine slartgp	(	real	f,
		real	g,
		real	cs,
		real	sn,
		real	r )

SLARTGP generates a plane rotation so that the diagonal is nonnegative.

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Purpose:

!>
!> SLARTGP generates a plane rotation so that
!>
!>    [  CS  SN  ]  .  [ F ]  =  [ R ]   where CS**2 + SN**2 = 1.
!>    [ -SN  CS  ]     [ G ]     [ 0 ]
!>
!> This is a slower, more accurate version of the Level 1 BLAS routine SROTG,
!> with the following other differences:
!>    F and G are unchanged on return.
!>    If G=0, then CS=(+/-)1 and SN=0.
!>    If F=0 and (G .ne. 0), then CS=0 and SN=(+/-)1.
!>
!> The sign is chosen so that R >= 0.
!> 

Parameters

[in]	F	!> F is REAL !> The first component of vector to be rotated. !>
[in]	G	!> G is REAL !> The second component of vector to be rotated. !>
[out]	CS	!> CS is REAL !> The cosine of the rotation. !>
[out]	SN	!> SN is REAL !> The sine of the rotation. !>
[out]	R	!> R is REAL !> The nonzero component of the rotated vector. !> !> This version has a few statements commented out for thread safety !> (machine parameters are computed on each entry). 10 feb 03, SJH. !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.