1SROTMG(1)                        BLAS routine                        SROTMG(1)
2
3
4

NAME

6       SROTMG  -  CONSTRUCT  THE MODIFIED GIVENS TRANSFORMATION MATRIX H WHICH
7       ZEROS  THE SECOND COMPONENT OF THE 2-VECTOR (SQRT(SD1)*SX1,SQRT(SD2)*
8

SYNOPSIS

10       SUBROUTINE SROTMG(SD1,SD2,SX1,SY1,SPARAM)
11
12           REAL                                  SD1,SD2,SX1,SY1
13
14           REAL                                  SPARAM(5)
15

PURPOSE

17          CONSTRUCT THE MODIFIED GIVENS TRANSFORMATION MATRIX H WHICH ZEROS
18          THE SECOND COMPONENT OF THE 2-VECTOR  (SQRT(SD1)*SX1,SQRT(SD2)*
19          SY2)**T.
20          WITH SPARAM(1)=SFLAG, H HAS ONE OF THE FOLLOWING FORMS..
21
22          SFLAG=-1.E0     SFLAG=0.E0        SFLAG=1.E0     SFLAG=-2.E0
23
24            (SH11  SH12)    (1.E0  SH12)    (SH11  1.E0)    (1.E0  0.E0)
25          H=(          )    (          )    (          )    (          )
26            (SH21  SH22),   (SH21  1.E0),   (-1.E0 SH22),   (0.E0  1.E0).
27          LOCATIONS 2-4 OF SPARAM CONTAIN SH11,SH21,SH12, AND SH22
28          RESPECTIVELY. (VALUES OF 1.E0, -1.E0, OR 0.E0 IMPLIED BY THE
29          VALUE OF SPARAM(1) ARE NOT STORED IN SPARAM.)
30
31          THE VALUES OF GAMSQ AND RGAMSQ SET IN THE DATA STATEMENT MAY BE
32          INEXACT.  THIS IS OK AS THEY ARE ONLY USED FOR TESTING THE SIZE
33          OF SD1 AND SD2.  ALL ACTUAL SCALING OF DATA IS DONE USING GAM.
34
35
36

ARGUMENTS

38       SD1    (input/output) REAL
39
40       SD2    (input/output) REAL
41
42       SX1    (input/output) REAL
43
44       SY1    (input) REAL
45
46              SPARAM (input/output)  REAL array, dimension  5  SPARAM(1)=SFLAG
47              SPARAM(2)=SH11 SPARAM(3)=SH21 SPARAM(4)=SH12 SPARAM(5)=SH22
48
49
50
51BLAS routine                     November 2008                       SROTMG(1)