srotm (l) - Linux Manuals

srotm: APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX (SX**T) , WHERE **T INDICATES TRANSPOSE

NAME

SROTM - APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX (SX**T) , WHERE **T INDICATES TRANSPOSE

SYNOPSIS

SUBROUTINE SROTM(N,SX,INCX,SY,INCY,SPARAM)

    

INTEGER INCX,INCY,N

    

REAL SPARAM(5),SX(1),SY(1)

PURPOSE

APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX
(DX**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.

ARGUMENTS

N (input) INTEGER

number of elements in input vector(s)

SX (input/output) REAL array, dimension N

double precision vector with 5 elements

INCX (input) INTEGER

storage spacing between elements of SX

SY (input/output) REAL array, dimension N

double precision vector with N elements

INCY (input) INTEGER

storage spacing between elements of SY

SPARAM (input/output) REAL array, dimension 5 SPARAM(1)=SFLAG SPARAM(2)=SH11 SPARAM(3)=SH21 SPARAM(4)=SH12 SPARAM(5)=SH22