Contents

• NAME
• SYNOPSIS
• PURPOSE
• ARGUMENTS

NAME

     zgthr - Gathers specified elements from y into x.

SYNOPSIS

      SUBROUTINE ZGTHR(NZ, Y, X, INDX)

      DOUBLE COMPLEX Y(*), X(*)
      INTEGER NZ
      INTEGER INDX(*)

      SUBROUTINE ZGTHR_64(NZ, Y, X, INDX)

      DOUBLE COMPLEX Y(*), X(*)
      INTEGER*8 NZ
      INTEGER*8 INDX(*)

     F95 INTERFACE
      SUBROUTINE GTHR([NZ], Y, X, INDX)

      COMPLEX(8), DIMENSION(:) :: Y, X
      INTEGER :: NZ
      INTEGER, DIMENSION(:) :: INDX

      SUBROUTINE GTHR_64([NZ], Y, X, INDX)

      COMPLEX(8), DIMENSION(:) :: Y, X
      INTEGER(8) :: NZ
      INTEGER(8), DIMENSION(:) :: INDX

PURPOSE

     ZGTHR - Gathers the specified elements from a vector y in
     full storage form into a vector x in compressed form.  Only
     the elements of y whose indices are listed in indx are
     referenced.

      do i = 1, n
        x(i) = y(indx(i))
      enddo

ARGUMENTS

     NZ (input) - INTEGER
             Number of elements in the compressed form.
             Unchanged on exit.

     Y (input)
             Vector in full storage form.  Unchanged on exit.

     X (output)
             Vector in compressed form.  Contains elements of y
             whose indices are listed in indx on exit.
     INDX (input) - INTEGER
             Vector containing the indices of the compressed
             form.  It is assumed that the elements in INDX are
             distinct and greater than zero.  Unchanged on exit.