dlartgp()

subroutine dlartgp	(	double precision	F,
		double precision	G,
		double precision	CS,
		double precision	SN,
		double precision	R
	)

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

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Purpose:

 DLARTGP 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 DROTG,
 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 DOUBLE PRECISION The first component of vector to be rotated.
[in]	G	G is DOUBLE PRECISION The second component of vector to be rotated.
[out]	CS	CS is DOUBLE PRECISION The cosine of the rotation.
[out]	SN	SN is DOUBLE PRECISION The sine of the rotation.
[out]	R	R is DOUBLE PRECISION 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.