cblas_?roti

Syntax

void cblas_sroti (const MKL_INT nz, float *x, const MKL_INT *indx, float *y, const float c, const float s);

void cblas_droti (const MKL_INT nz, double *x, const MKL_INT *indx, double *y, const double c, const double s);

Include Files

• mkl.h

Description

The ?roti routines apply the Givens rotation to elements of two real vectors, x (in compressed form nz, x, indx) and y (in full storage form):

x[i] = c*x[i] + s*y[indx[i]]

y[indx[i]] = c*y[indx[i]]- s*x[i]

The routines reference only the elements of y whose indices are listed in the array indx. The values in indx must be distinct.

Input Parameters

nz

The number of elements in x and indx.

x

Array, size at least nz.

indx

Specifies the indices for the elements of x.

Array, size at least nz.

y

Array, size at least max(indx[i]).

c

A scalar.

s

A scalar.

Output Parameters

x and y

The updated arrays.