CSCTR(3)     SPARSE BLAS routine of NEC Numeric Library Collection    CSCTR(3)



NAME
       CSCTR - Scatter a sparse vector from compressed form

SYNOPSIS
       SUBROUTINE CSCTR( NZ, X, INDX, Y )

           INTEGER        NZ, INDX

           COMPLEX        X, Y

PURPOSE
       Scatter(copy)  the  components  of a sparse vector stored in compressed
       form into specified components of a vector in full-storage form.  If  y
       is initially the zero vector, then CSCTR performs

                     y := x

       which is represented by the following FORTRAN

                Y( INDX(I) ) = X(I)

                for I = 1, ..., NZ.

       In  typical use of full-form temporary vectors, the vector is initially
       set to zero. CSCTR is used to initialize the  interesting  entries  for
       processing. At the completion of processing, CGTHRZ is used to move the
       interesting values back into the sparse data structures and  simultane-
       ously  reset the full-form vector to its initial, zero, state for later
       use.

       The values of INDX must be distinct to allow consistent vector or  par-
       allel execution.


ARGUMENTS
       NZ      (input) INTEGER
               Number of elements to be scattered from compressed form.

       X       (input) COMPLEX
               Array containing the values to be scattered from the compressed
               form into full storage form.

       INDX    (input) INTEGER
               Array containing the indices of the values to be scattered from
               compressed  form.  It  is assumed that the elements in INDX are
               distinct.

       Y       (output) COMPLEX
               Array whose elements specified by INDX have  been  set  to  the
               corresponding  entries of X. Only the elements corresponding to
               the indices in INDX have been modified.

FURTHER DETAILS
       Sparse BLAS algorithm is from  ACM  algorithm  692  by  D.  Dodson,  R.
       Grimes, and J. Lewis.




SPARSE BLAS routine             31 October 2017                       CSCTR(3)