1SROTMG(1)                        BLAS routine                        SROTMG(1)
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NAME

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

10       SUBROUTINE SROTMG(SD1,SD2,SX1,SY1,SPARAM)
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12           REAL                                  SD1,SD2,SX1,SY1
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14           REAL                                  SPARAM(5)
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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..
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22          SFLAG=-1.E0     SFLAG=0.E0        SFLAG=1.E0     SFLAG=-2.E0
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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.)
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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.
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ARGUMENTS

38       SD1    (input/output) REAL
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40       SD2    (input/output) REAL
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42       SX1    (input/output) REAL
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44       SY1    (input) REAL
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46              SPARAM (input/output)  REAL array, dimension  5  SPARAM(1)=SFLAG
47              SPARAM(2)=SH11 SPARAM(3)=SH21 SPARAM(4)=SH12 SPARAM(5)=SH22
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51BLAS routine                     February 2007                       SROTMG(1)