NAME

       rotm - rotm: apply modified (fast) plane rotation

SYNOPSIS

   Functions
       subroutine drotm (n, dx, incx, dy, incy, dparam)
           DROTM
       subroutine srotm (n, sx, incx, sy, incy, sparam)
           SROTM

Detailed Description

Function Documentation

   subroutine drotm (integer n, double precision, dimension(*) dx, integer incx, double
       precision, dimension(*) dy, integer incy, double precision, dimension(5) dparam)
       DROTM

       Purpose:

               APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX

               (DX**T) , WHERE **T INDICATES TRANSPOSE. THE ELEMENTS OF DX ARE IN
               (DY**T)

               DX(LX+I*INCX), I = 0 TO N-1, WHERE LX = 1 IF INCX .GE. 0, ELSE
               LX = (-INCX)*N, AND SIMILARLY FOR SY USING LY AND INCY.
               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).
               SEE DROTMG FOR A DESCRIPTION OF DATA STORAGE IN DPARAM.

       Parameters
           N

                     N is INTEGER
                    number of elements in input vector(s)

           DX

                     DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) )

           INCX

                     INCX is INTEGER
                    storage spacing between elements of DX

           DY

                     DY is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCY ) )

           INCY

                     INCY is INTEGER
                    storage spacing between elements of DY

           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 srotm (integer n, real, dimension(*) sx, integer incx, real, dimension(*) sy,
       integer incy, real, dimension(5) sparam)
       SROTM

       Purpose:

               APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX

               (SX**T) , WHERE **T INDICATES TRANSPOSE. THE ELEMENTS OF SX ARE IN
               (SX**T)

               SX(LX+I*INCX), I = 0 TO N-1, WHERE LX = 1 IF INCX .GE. 0, ELSE
               LX = (-INCX)*N, AND SIMILARLY FOR SY USING USING LY AND INCY.
               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).
               SEE  SROTMG FOR A DESCRIPTION OF DATA STORAGE IN SPARAM.

       Parameters
           N

                     N is INTEGER
                    number of elements in input vector(s)

           SX

                     SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )

           INCX

                     INCX is INTEGER
                    storage spacing between elements of SX

           SY

                     SY is REAL array, dimension ( 1 + ( N - 1 )*abs( INCY ) )

           INCY

                     INCY is INTEGER
                    storage spacing between elements of SY

           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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