DROTM(1) BLAS routine DROTM(1)NAME
DROTM - APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N
MATRIX (DX**T) , WHERE **T INDICATES TRANSPOSE
SYNOPSIS
SUBROUTINE DROTM(N,DX,INCX,DY,INCY,DPARAM)
INTEGER INCX,INCY,N
DOUBLE PRECISION
DPARAM(5),DX(1),DY(1)PURPOSE
APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX
(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.
ARGUMENTS
N (input) INTEGER
number of elements in input vector(s)
DX (input/output) DOUBLE PRECISION array, dimension N
double precision vector with 5 elements
INCX (input) INTEGER
storage spacing between elements of DX
DY (input/output) DOUBLE PRECISION array, dimension N
double precision vector with N elements
INCY (input) INTEGER
storage spacing between elements of DY
DPARAM (input/output) DOUBLE PRECISION array, dimension 5
DPARAM(1)=DFLAG DPARAM(2)=DH11 DPARAM(3)=DH21 DPARAM(4)=DH12
DPARAM(5)=DH22
BLAS routine November 2008 DROTM(1)
