NAG FL Interface
f06gtf (zaxpyi)

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FL Name Style:

FL Specification Language:

1 Purpose

f06gtf adds a scaled sparse complex vector to an unscaled complex vector.

2 Specification

Fortran Interface
Subroutine f06gtf ( nz, a, x, indx, y)
Integer, Intent (In) :: nz, indx(*)
Complex (Kind=nag_wp), Intent (In) :: a, x(*)
Complex (Kind=nag_wp), Intent (Inout) :: y(*)
C Header Interface
#include <nag.h>
void  f06gtf_ (const Integer *nz, const Complex *a, const Complex x[], const Integer indx[], Complex y[])
The routine may be called by the names f06gtf, nagf_blas_zaxpyi or its BLAS name zaxpyi.

3 Description

f06gtf performs the operation
where x is a sparse complex vector stored in compressed form, and y is a complex vector in full storage form.

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: a Complex (Kind=nag_wp) Input
On entry: the scalar α.
3: x(*) Complex (Kind=nag_wp) array Input
Note: the dimension of the array x must be at least max(1,nz) .
On entry: the compressed vector x. x contains xi for iJ.
4: indx(*) Integer array Input
Note: the dimension of the array indx must be at least max(1,nz) .
On entry: the indices of the elements in the compressed vector x.
Constraint: the indices must be distinct.
5: y(*) Complex (Kind=nag_wp) array Input/Output
Note: the dimension of the array y must be at least maxk{indx(k)} .
On entry: the vector y. Only elements corresponding to indices in indx are accessed.
On exit: the updated vector y.

6 Error Indicators and Warnings


7 Accuracy

Not applicable.

8 Parallelism and Performance

f06gtf is not threaded in any implementation.

9 Further Comments


10 Example