SROTMG(3)

SYNOPSIS
SUBROUTINE SROTMG (SD1, SD2, SX1, SY1, SPARAM)

NAME
srotmg - Construct a modified Givens transformation.

LIBRARY
SLATEC (BLAS)

CATEGORY
D1B10

TYPE
SINGLE PRECISION (SROTMG-S, DROTMG-D)

KEYWORDS
BLAS, LINEAR ALGEBRA, MODIFIED GIVENS ROTATION, VECTOR

AUTHOR
Lawson, C. L., (JPL) Hanson, R. J., (SNLA) Kincaid, D. R., (U. of Texas) Krogh, F. T., (JPL)

DESCRIPTION
B L A S Subprogram Description of Parameters --Input-- SD1 single precision scalar SD2 single precision scalar SX1 single precision scalar SY2 single precision scalar SPARAM S.P. 5-vector. SPARAM(1)=SFLAG defined below. Locations 2-5 contain the rotation matrix. --Output-- SD1 changed to represent the effect of the transformation SD2 changed to represent the effect of the transformation SX1 changed to represent the effect of the transformation SY2 unchanged Construct the modified Givens transformation matrix H which zeros the second component of the 2-vector (SQRT(SD1)*SX1,SQRT(SD2)* SY2)**T. With SPARAM(1)=SFLAG, H has one of the following forms: SFLAG=-1.E0 SFLAG=0.E0 SFLAG=1.E0 SFLAG=-2.E0 (SH11 SH12) (1.E0 SH12) (SH11 1.E0) (1.E0 0.E0) H=( ) ( ) ( ) ( ) (SH21 SH22), (SH21 1.E0), (-1.E0 SH22), (0.E0 1.E0). Locations 2-5 of SPARAM contain SH11, SH21, SH12, and SH22, respectively. (Values of 1.E0, -1.E0, or 0.E0 implied by the value of SPARAM(1) are not stored in SPARAM.)

REFERENCES
C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T. Krogh, Basic linear algebra subprograms for Fortran usage, Algorithm No. 539, Transactions on Mathematical Software 5, 3 (September 1979), pp. 308-323.

ROUTINES CALLED
(NONE)

REVISION HISTORY (YYMMDD)
780301 DATE WRITTEN
861211 REVISION DATE from Version 3.2
891214 Prologue converted to Version 4.0 format. (BAB)
920316 Prologue corrected. (WRB)
920501 Reformatted the REFERENCES section. (WRB)