1DROTM(1)                         BLAS routine                         DROTM(1)
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NAME

6       DROTM  -  APPLY  THE  MODIFIED  GIVENS TRANSFORMATION, H, TO THE 2 BY N
7       MATRIX   (DX**T) , WHERE **T INDICATES TRANSPOSE
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SYNOPSIS

10       SUBROUTINE DROTM(N,DX,INCX,DY,INCY,DPARAM)
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12           INTEGER                                INCX,INCY,N
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14           DOUBLE                                 PRECISION
15                                                  DPARAM(5),DX(1),DY(1)
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PURPOSE

18          APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX
19          (DY**T)
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21          DX(LX+I*INCX), I = 0 TO N-1, WHERE LX = 1 IF INCX .GE. 0, ELSE
22          LX = (-INCX)*N, AND SIMILARLY FOR SY USING LY AND INCY.
23          WITH DPARAM(1)=DFLAG, H HAS ONE OF THE FOLLOWING FORMS..
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25          DFLAG=-1.D0     DFLAG=0.D0        DFLAG=1.D0     DFLAG=-2.D0
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27            (DH11  DH12)    (1.D0  DH12)    (DH11  1.D0)    (1.D0  0.D0)
28          H=(          )    (          )    (          )    (          )
29            (DH21  DH22),   (DH21  1.D0),   (-1.D0 DH22),   (0.D0  1.D0).
30          SEE DROTMG FOR A DESCRIPTION OF DATA STORAGE IN DPARAM.
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ARGUMENTS

34       N      (input) INTEGER
35              number of elements in input vector(s)
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37       DX     (input/output) DOUBLE PRECISION array, dimension N
38              double precision vector with 5 elements
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40       INCX   (input) INTEGER
41              storage spacing between elements of DX
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43       DY     (input/output) DOUBLE PRECISION array, dimension N
44              double precision vector with N elements
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46       INCY   (input) INTEGER
47              storage spacing between elements of DY
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49              DPARAM  (input/output)   DOUBLE  PRECISION  array,  dimension  5
50              DPARAM(1)=DFLAG  DPARAM(2)=DH11  DPARAM(3)=DH21   DPARAM(4)=DH12
51              DPARAM(5)=DH22
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55BLAS routine                     November 2008                        DROTM(1)