Applied Modified Given's Transformation

Calling Sequence

CALL DROTM	(N, DX, INCX, DY, INCY, DPARAM)
CALL SROTM	(N, SX, INCX, SY, INCY, SPARAM)
void drotm	(int n, double *dx, int incx, double *dy, int incy, double *dparam)
void srotm	(int n, float *sx, int incx, float *sy, int incy, float sc, float *sparam)

Arguments

N	Number of elements in the vector. N 0.
xX	Input vector X; the size of array X must be at least max(1,N*|INCX|).
INCX	Specifies the storage spacing between successive elements of the vector X. A value of one indicates that the elements of the vector are consecutive in memory.
	If X refers to a two-dimensional array and the value of INCX is equal to the leading dimension of X then the elements of the vector will be a row of X.
	If X refers to a two-dimensional array and the value of INCX is equal to the leading dimension of X plus one then the elements of the vector will be a diagonal of X.
xY	Result vector Y; the size of array Y must be at least max(1,N*|INCY|).
INCY	Specifies the storage spacing between successive elements of the vector Y. A value of one indicates that the elements of the vector are consecutive in memory.
	If Y refers to a two-dimensional array and the value of INCY is equal to the leading dimension of Y then the elements of the vector will be a row of Y.
	If Y refers to a two-dimensional array and the value of INCY is equal to the leading dimension of Y plus one then the elements of the vector will be a diagonal of Y.
xPARAM	Value of the PARAM argument from xROTMG.

Sample Program

PROGRAM TEST

IMPLICIT NONE

C

INTEGER N

PARAMETER (N = 4)

C

DOUBLE PRECISION B1, B2, D1, D2, PARAM(5), X(N), Y(N)

INTEGER I, INCX, INCY

C

EXTERNAL DROTM, DROTMG

C

C Initialize the arrays X and Y to store the vectors x and y

C shown below.

C

C 5 2

C x = 5 y = 4

C 5 8

C 5 16

C

DATA X / 5.0D0, 5.0D0, 5.0D0, 5.0D0 /

DATA Y / 2.0D0, 4.0D0, 8.0D0, 1.6D1 /

C

PARAM(1) = -2

PRINT 1000

PRINT 1010, (X(I), Y(I), I = 1, N)

C

C Set up the rotation that will eliminate the third element.

C

D1 = 1.0D0

D2 = 1.0D0

B1 = X(3)

B2 = Y(3)

CALL DROTMG (D1, D2, B1, B2, PARAM)

C

C Apply the rotation to eliminate the third element and print

C the results.

C

INCX = 1

INCY = 1

CALL DROTM (N, X, INCX, Y, INCY, PARAM)

PRINT 1020

PRINT 1010, (X(I), Y(I), I = 1, N)

C

1000 FORMAT (1X, 6X, 'x', 9X, 'y')

1010 FORMAT (2(3X, F7.4))

1020 FORMAT (/1X, 6X, 'x''', 8X, 'y''')

C

END

Sample Output

x y
5.0000 2.0000
5.0000 4.0000
5.0000 8.0000
5.0000 16.0000
x' y'
5.1250 -3.7500
7.1250 -2.5000
11.1250 0.0000
19.1250 5.0000