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?rotm

Perform conversion based on the modified Givens.

x and y are vectors containing n elements, and h is a transformation matrix element.

Interface Definition

C interface:

void cblas_srotm(const BLASINT N, float *X, const BLASINT incX, float *Y, const BLASINT incY, const float *P);

void cblas_drotm(const BLASINT N, double *X, const BLASINT incX, double *Y, const BLASINT incY, const double *P);

Fortran interface:

CALL SROTM(N, SX, INCX, SY, INCY, DTEMP)

CALL DROTM(N, SX, INCX, SY, INCY, DTEMP)

Parameters

Parameter

Type

Description

Input/Output

N

Integer

Number of elements in the X vector

Input

X
  • For srotm, X is of single-precision floating-point type.
  • For drotm, X is of double-precision floating-point type.

Vector X. The vector size is at least (1+(n-1)*abs(incx)).

Input/Output

incX

Integer

Increment for the elements of vector x

Input

Y
  • For srotm, Y is of single-precision floating-point type.
  • For drotm, Y is of double-precision floating-point type.

Vector Y. The vector scale is at least (1+(n-1)*abs(incy)).

Input/Output

incY

Integer

Increment for elements in vector Y

Input

P
  • For srotm, P is of single-precision floating-point type.
  • For drotm, P is of double-precision floating-point type.

Conversion matrix H

Input

Dependencies

#include "kblas.h"

Examples

C interface:

    double d1 = 10.0, d2 = 2.0;
    double x1 = 2.0, x2 = 1.0; 
    double p[5]; 
    int n = 5, incx = 1, incy = 1; 
    double x[5]={1.0, 2.0, 1.0, 3.0, 1.0}; 
    double y[5]={3.0, 1.0, 1.0, 5.0, 1.0}; 
 
    cblas_drotmg(&d1, &d2, &x1, x2, p); 
    cblas_drotm(n, x, incx, y, incy, p); 
    /* 
     * Output x:  1.300000,  2.100000, 1.100000,  3.500000, 1.100000 
     * Output y:  2.500000,  0.000000, 0.500000,  3.500000, 0.500000 
     */

Fortran interface:

      REAL(8) :: D1=10.0 
      REAL(8) :: D2=2.0 
      REAL(8) :: X1=2.0 
      REAL(8) :: X2=1.0 
      REAL(8) :: P(5) 
      INTEGER :: N=5 
      INTEGER :: INCX=1 
      INTEGER :: INCY=1 
      REAL(8) :: X(5) 
      DATA X/1.0, 2.0, 1.0, 3.0, 1.0/ 
      REAL(8) :: Y(5) 
      DATA Y/3.0, 1.0, 1.0, 5.0, 1.0/ 
      EXTERNAL DROTMG 
      CALL DROTMG(D1, D2, X1, X2, P) 
      EXTERNAL DROTM 
      CALL DROTM(N, X, INCX, Y, INCY, P) 
 
*     Output X:  1.300000,  2.100000, 1.100000,  3.500000, 1.100000 
*     Output Y:  2.500000,  0.000000, 0.500000,  3.500000, 0.500000