f06guf (zgthr) (PDF version)
F06 (blas) Chapter Contents
F06 (blas) Chapter Introduction
NAG Library Manual
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NAG Library Routine Document
f06guf (zgthr)
▸
▿
Contents
1
Purpose
2
Specification
3
Description
4
References
5
Arguments
6
Error Indicators and Warnings
7
Accuracy
8
Parallelism and Performance
9
Further Comments
10
Example
1
Purpose
f06guf (zgthr)
gathers specified (usually nonzero) elements of a complex vector
y
in full storage form into a sparse complex vector
x
in compressed form.
2
Specification
Fortran Interface
Subroutine f06guf (
nz
,
y
,
x
,
indx
)
Integer, Intent (In)
::
nz
,
indx(*)
Complex (Kind=nag_wp), Intent (In)
::
y(*)
Complex (Kind=nag_wp), Intent (Inout)
::
x(*)
C Header Interface
#include nagmk26.h
void
f06guf_ (
const Integer *
nz
,
const Complex
y
[]
,
Complex
x
[]
,
const Integer
indx
[]
)
The routine may be called by its BLAS name
zgthr
.
3
Description
None.
4
References
Dodson D S, Grimes R G and Lewis J G (1991) Sparse extensions to the Fortran basic linear algebra subprograms
ACM Trans. Math. Software
17
253–263
5
Arguments
1:
nz
– Integer
Input
On entry
: the number of nonzeros in the sparse vector
x
.
2:
y
*
– Complex (Kind=nag_wp) array
Input
Note:
the dimension of the array
y
must be at least
max
k
indx
k
.
On entry
: the vector
y
. Only elements corresponding to indices in
indx
are accessed.
3:
x
*
– Complex (Kind=nag_wp) array
Output
Note:
the dimension of the array
x
must be at least
max
1
,
nz
.
On exit
: the compressed vector
x
.
4:
indx
*
– Integer array
Input
Note:
the dimension of the array
indx
must be at least
max
1
,
nz
.
On entry
:
indx
must contain the set of indices
J
.
6
Error Indicators and Warnings
None.
7
Accuracy
Not applicable.
8
Parallelism and Performance
f06guf (zgthr)
is not threaded in any implementation.
9
Further Comments
None.
10
Example
None.
f06guf (zgthr) (PDF version)
F06 (blas) Chapter Contents
F06 (blas) Chapter Introduction
NAG Library Manual
© The Numerical Algorithms Group Ltd, Oxford, UK. 2017