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C Library Functions  - srotmg (3)

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NAME

srotmg(3f) - [BLAS:SINGLE_BLAS_LEVEL1] Generate a modified Given’s rotation.

CONTENTS

Synopsis
Definition
Options
Authors
See Also

SYNOPSIS

subroutine srotmg(sd1,sd2,sx1,sy1,sparam)

      .. Scalar Arguments ..
      real,intent(inout) :: sd1,sd2,sx1
      real,intent(in)    :: sy1
      ..
      .. Array Arguments ..
      real,intent(out)   :: sparam(5)
      ..

DEFINITION

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 2-4 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.)

the values of GAMSQ and RGAMSQ set in the data statement may be inexact. This is OK as they are only used for testing the size of SD1 and SD2. All actual scaling of data is done using GAM.

OPTIONS

SD1

          SD1 is REAL

SD2

          SD2 is REAL

SX1

          SX1 is REAL

SY1

          SY1 is REAL

    SPARAM

SPARAM is REAL array, dimension (5) SPARAM(1)=SFLAG SPARAM(2)=SH11 SPARAM(3)=SH21 SPARAM(4)=SH12 SPARAM(5)=SH22

AUTHORS

o	Univ. of Tennessee
o	Univ. of California Berkeley
o	Univ. of Colorado Denver
o	NAG Ltd.

 date:November 2017

SEE ALSO

Online html documentation available at http://www.netlib.org/lapack/explore-html/

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Nemo Release 3.1

srotmg (3)

February 23, 2025

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