SBLAS(3)                    MathKeisan SPARSE BLAS                    SBLAS(3)



NAME
       SBLAS - Sparse BLAS (Basic Linear Algebra Subprograms)


DESCRIPTION
       Sparse BLAS is a set of subroutines used to perform sparse vector oper-
       ations.

       In sparse linear algebra, large savings in computer time and memory are
       realized  by  storing  and  operating  on  only the interesting(usually
       nonzero) components of vectors. The most common method for representing
       a  sparse  vector  uses a FORTRAN array just long enough to contain the
       interesting components and a companion array of indices that  maps  the
       stored values into their proper positions within vectors. Letting NZ be
       the number of interesting components of x, X be the  FORTRAN  array  in
       which  they  are  stored,  and  INDX be the FORTRAN array of indices, a
       sparse vector is represented by the triple (NZ, X, INDX). For  example,
       if
               x = (0, 4, 0, 0, 1, 0, 0, 0, 6, 0)

       and if the interesting components of x are the nonzero ones, then

                        NZ = 3
                         X = (4, 1, 6)
                      INDX = (2, 5, 9)

       so that

                   X       = X(i)
                    INDX(i)

       The  sparse  BLAS  includes  the following individual man pages for the
       corresponding subroutines or functions:

       ----------------------------------------------------------------
       Function               Single  Double  Complex  Complex*16
       ----------------------------------------------------------------
       Dot product            SDOTI   DDOTI   CDOTUI   ZDOTUI
           (conjugate)                        CDOTCI   ZDOTCI
       ----------------------------------------------------------------
       Scalar times a vector
         added to a vector    SAXPYI  DAXPYI  CAXPYI   ZAXPYI
       ----------------------------------------------------------------
       Apply Givens rotation  SROTI   DROTI
       ----------------------------------------------------------------
       Gather y into x        SGTHR   DGTHR   CGTHR    ZGTHR
         and zero the vector  SGTHRZ  DGTHRZ  CGTHRZ   ZGTHRZ
       ----------------------------------------------------------------
       Scatter x into y       SSCTR   DSCTR   CSCTR    ZSCTR
       ----------------------------------------------------------------

       To read the man page for SDOTI, for example, type "man sdoti".

       The sparse BLAS included in the librares is from  ACM  "algorithm  692:
       model implementation and test package for the sparse basic linear alge-
       bra subprograms" by D. Dodson, R. Grimes, and J. Lewis.


NOTES
       For more information, see:

       Dodson, D. S., Grimes, R. G., and Lewis, J. G. Sparse extensions to the
       FORTRAN  basic  linear algebra subprograms. ACM Trans. Math. Softw. 17,
       2(June 1991), pp. 253-263.

       If you have any problems with this library, please contact us at:

              http://www.mathkeisan.com/

SEE ALSO
       mathkeisan(3), MathKeisan User's Guide at:

              http://www.mathkeisan.com/

       The command:

              man mathkeisan

       gives more information on linking.



MathKeisan                         June 1991                          SBLAS(3)