NAME

BLAS/SRC/drotm.f

SYNOPSIS

Functions/Subroutines

subroutine drotm (n, dx, incx, dy, incy, dparam)
DROTM

Function/Subroutine 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 is INTEGER


         number of elements in input vector(s)



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

INCX



          INCX is INTEGER


         storage spacing between elements of DX



          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.

Definition at line 95 of file drotm.f.

Author