NAME

       rotmg - rotmg: generate modified (fast) plane rotation

SYNOPSIS

   Functions
       subroutine drotmg (dd1, dd2, dx1, dy1, dparam)
           DROTMG
       subroutine srotmg (sd1, sd2, sx1, sy1, sparam)
           SROTMG

Detailed Description

Function Documentation

   subroutine drotmg (double precision dd1, double precision dd2, double precision dx1, double
       precision dy1, double precision, dimension(5) dparam)
       DROTMG

       Purpose:

               CONSTRUCT THE MODIFIED GIVENS TRANSFORMATION MATRIX H WHICH ZEROS
               THE SECOND COMPONENT OF THE 2-VECTOR  (DSQRT(DD1)*DX1,DSQRT(DD2)*>    DY2)**T.
               WITH DPARAM(1)=DFLAG, H HAS ONE OF THE FOLLOWING FORMS..

               DFLAG=-1.D0     DFLAG=0.D0        DFLAG=1.D0     DFLAG=-2.D0

                 (DH11  DH12)    (1.D0  DH12)    (DH11  1.D0)    (1.D0  0.D0)
               H=(          )    (          )    (          )    (          )
                 (DH21  DH22),   (DH21  1.D0),   (-1.D0 DH22),   (0.D0  1.D0).
               LOCATIONS 2-4 OF DPARAM CONTAIN DH11, DH21, DH12, AND DH22
               RESPECTIVELY. (VALUES OF 1.D0, -1.D0, OR 0.D0 IMPLIED BY THE
               VALUE OF DPARAM(1) ARE NOT STORED IN DPARAM.)

               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 DD1 AND DD2.  ALL ACTUAL SCALING OF DATA IS DONE USING GAM.

       Parameters
           DD1

                     DD1 is DOUBLE PRECISION

           DD2

                     DD2 is DOUBLE PRECISION

           DX1

                     DX1 is DOUBLE PRECISION

           DY1

                     DY1 is DOUBLE PRECISION

           DPARAM

                     DPARAM is DOUBLE PRECISION array, dimension (5)
                DPARAM(1)=DFLAG
                DPARAM(2)=DH11
                DPARAM(3)=DH21
                DPARAM(4)=DH12
                DPARAM(5)=DH22

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

   subroutine srotmg (real sd1, real sd2, real sx1, real sy1, real, dimension(5) sparam)
       SROTMG

       Purpose:

               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.

       Parameters
           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

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

Author

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