Performs modified Givens rotation of points in the plane.


void cblas_srotm (const MKL_INT n, float *x, const MKL_INT incx, float *y, const MKL_INT incy, const float *param);

void cblas_drotm (const MKL_INT n, double *x, const MKL_INT incx, double *y, const MKL_INT incy, const double *param);

Include Files

  • mkl.h


Given two vectors x and y, each vector element of these vectors is replaced as follows:

for i=1 to n, where H is a modified Givens transformation matrix whose values are stored in the param[1] through param[4] array. See discussion on the param argument.

Input Parameters


Specifies the number of elements in vectors x and y.


Array, size at least (1 + (n -1)*abs(incx)).


Specifies the increment for the elements of x.


Array, size at least (1 + (n -1)*abs(incy)).


Specifies the increment for the elements of y.


Array, size 5.

The elements of the param array are:

param[0] contains a switch, flag. param[1-4] contain h11, h21, h12, and h22, respectively, the components of the array H.

Depending on the values of flag, the components of H are set as follows:

flag = -1.0:

flag = 0.0:

flag = 1.0:

flag = -2.0:

In the last three cases, the matrix entries of 1.0, -1.0, and 0.0 are assumed based on the value of flag and are not required to be set in the param vector.

Output Parameters


Each element x[i] is replaced by h11*x[i] + h12*y[i].


Each element y[i] is replaced by h21*x[i] + h22*y[i].

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