Developer Reference for Intel® oneAPI Math Kernel Library for C
?gthr
Gathers a full-storage sparse vector’s elements into compressed form.
Syntax
void cblas_sgthr ( const MKL_INT nz,
const float *y,
float *x,
const MKL_INT *indx );
void cblas_sgthr ( const MKL_INT nz,
const double *y,
double *x,
const MKL_INT *indx );
void cblas_cgthr ( const MKL_INT nz,
const void *y,
void *x,
const MKL_INT *indx );
void cblas_zgthr ( const MKL_INT nz,
const void *y,
void *x,
const MKL_INT *indx );
Include Files
mkl.h
Description
The ?gthr routines gather the specified elements of a full-storage sparse vector \(y\) into compressed form ( nz, x, indx). The routines reference only the elements of \(y\) whose indices are listed in the array \(indx\) :
\[x[i] = y[indx[i]] \text{, for } i=0,1,\dots,nz-1\]
Input Parameters
nz
The number of elements in x and indx and the number of elements to be gathered from y.
indx
Specifies the indices for the elements of x. Array, size at least nz .
y
Array, size at least \(\max(\text{indx}[i]) + 1\).
Output Parameters
x
Array, size at least nz . Contains the vector converted to the compressed form.
BLAS 95 Interface Notes
There exist FORTRAN 77 and FORTRAN 95 interfaces for this routine. See the Intel® oneMKL Fortran Developer Reference for details.