Contents

• NAME
• SYNOPSIS
• PURPOSE
• ARGUMENTS

NAME

     sdoti - Compute the indexed dot product.

SYNOPSIS

      REAL FUNCTION SDOTI(NZ, X, INDX, Y)

      REAL X(*), Y(*)
      INTEGER NZ
      INTEGER INDX(*)

      REAL FUNCTION SDOTI_64(NZ, X, INDX, Y)

      REAL X(*), Y(*)
      INTEGER*8 NZ
      INTEGER*8 INDX(*)

     F95 INTERFACE
      REAL FUNCTION DOTI([NZ], X, INDX, Y)

      REAL, DIMENSION(:) :: X, Y
      INTEGER :: NZ
      INTEGER, DIMENSION(:) :: INDX

      REAL FUNCTION DOTI_64([NZ], X, INDX, Y)

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

PURPOSE

     SDOTI Compute the indexed dot product of a real sparse
     vector x stored in compressed form with a real vector y in
     full storage form.

      dot = 0
      do i = 1, n
        dot = dot + x(i) * y(indx(i))
      enddo

ARGUMENTS

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

     X (input)
             Vector in compressed form.  Unchanged on exit.

     INDX (input)
             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.

     Y (input)
             Vector in full storage form.  Only the elements
             corresponding to the indices in INDX will be
             accessed.