cblas_?rotmg
cblas_?rotmg
Computes the parameters for a modified Givens rotation.
Syntax
void
cblas_srotmg
(
float
*d1
,
float
*d2
,
float
*x1
,
const
float
y1
,
float
*param
);
void
cblas_drotmg
(
double
*d1
,
double
*d2
,
double
*x1
,
const
double
y1
,
double
*param
);
Include Files
- mkl.h
Description
Given Cartesian coordinates () of an input vector,
x1
, y1
these
routines compute the components of a modified Givens transformation matrix H
that zeros the y
-component of the resulting vector:

Input Parameters
- d1
- Provides the scaling factor for thex-coordinate of the input vector.
- d2
- Provides the scaling factor for they-coordinate of the input vector.
- x1
- Provides thex-coordinate of the input vector.
- y1
- Provides they-coordinate of the input vector.
Output Parameters
- d1
- Provides the first diagonal element of the updated matrix.
- d2
- Provides the second diagonal element of the updated matrix.
- x1
- Provides thex-coordinate of the rotated vector before scaling.
- param
- Array, size 5.The elements of theparamarray are:contains a switch,param[0]flag. the other array elementscontain the components of the arrayparam[1-4]H:h11,h21,h12, andh22, respectively.Depending on the values offlag, the components ofHare 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 offlagand are not required to be set in theparamvector.