drotm (3) - Linux Manuals

NAME

drotm.f -

SYNOPSIS

Functions/Subroutines

subroutine drotm (N, DX, INCX, DY, INCY, DPARAM)
DROTM

Function/Subroutine Documentation

subroutine drotm (integerN, double precision, dimension(*)DX, integerINCX, double precision, dimension(*)DY, integerINCY, 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 N
         double precision vector with N elements

INCX

          INCX is INTEGER
         storage spacing between elements of DX

DY

          DY is DOUBLE PRECISION array, dimension N
         double precision vector with N elements

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.

Date:

November 2011

Definition at line 99 of file drotm.f.

Author

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