Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?gthrz
Gathers a sparse vector’s elements into compressed form, replacing them by zeros.
Syntax
call sgthrz ( nz, y, x, indx )
call dgthrz ( nz, y, x, indx )
call cgthrz ( nz, y, x, indx )
call zgthrz ( nz, y, x, indx )
res = gthrz ( x, indx, y )
Include Files
mkl.fi , mkl_blas.f90
Description
The ?gthrz routines gather the elements with indices specified by the array indx from a full-storage vector y into compressed form ( nz, x, indx ) and overwrite the gathered elements of y by zeros. Other elements of y are not referenced or modified (see also ?gthr (which gathers a full-storage sparse vector’s elements into compressed form but does apply zeros to y.) ).
\[x(i) = y(indx(i)); y(indx(i)) = 0 \text{, for } i=1,2,\dots,nz\]
Input Parameters
nz
INTEGER .
The number of elements in x and indx and the number of elements to be gathered from y.
indx
INTEGER.
Specifies the indices for the elements of x to be gathered from y. Array, size at least nz .
y
REAL |
for sgthrz |
DOUBLE PRECISION |
for dgthrz |
COMPLEX |
for cgthrz |
DOUBLE COMPLEX |
for zgthrz |
Array, size at least \(\max(\text{indx}(i))\).
Output Parameters
x
REAL |
for sgthr |
DOUBLE |
for dgthr |
COMPLEX |
for cgthr |
DOUBLE COMPLEX |
for zgthr |
Array, size at least nz . Contains the vector converted to the compressed form.
- y
-
The updated vector y.
BLAS 95 Interface Notes
Routines in Fortran 95 interface have fewer arguments in the calling sequence than their FORTRAN 77 counterparts. For general conventions applied to skip redundant or reconstructible arguments, see BLAS 95 Interface Conventions .
Specific details for the routine gthrz interface are the following:
- x
-
Holds the vector with the number of elements nz .
- indx
-
Holds the vector with the number of elements nz .
- y
-
Holds the vector with the number of elements nz .