sasum(3S)

NAME
     SASUM, DASUM, SCASUM, DZASUM - Sums the absolute value of elements in a
     real or complex vector

SYNOPSIS
     Single precision

          Fortran:
               real SASUM
               real sum
               sum = SASUM (n, x, incx)

          C/C++:
               #include <scsl_blas.h>
               float sasum( int n, float *x, int incx );

     Double precision

          Fortran:
               double precision DASUM
               double precision sum
               sum = DASUM (n, x, incx)

          C/C++:
               #include <scsl_blas.h>
               double dasum( int n, double *x, int incx );

     Single precision complex

          Fortran:
               real SCASUM
               real sum
               sum = SCASUM (n, x, incx)

          C/C++:
               #include <scsl_blas.h>
               float scasum( int n, scsl_complex *x, int incx );

          C++ STL:
               #include <complex.h>
               #include <scsl_blas.h>
               float scasum( int n, complex<float> *x, int incx );

     Double precision complex

          Fortran:
               double precision DZASUM
               double precision sum
               sum = DZASUM (n, x, incx)

          C/C++:
               #include <scsl_blas.h>
               double dzasum( int n, scsl_zomplex *x, int incx );

          C++ STL:
               #include <complex.h>
               #include <scsl_blas.h>
               double dzasum( int n, complex<double> *x, int incx );

IMPLEMENTATION
     These routines are part of the SCSL Scientific Library and can be loaded
     using either the -lscs or the -lscs_mp option.  The -lscs_mp option
     directs the linker to use the multi-processor version of the library.

     When linking to SCSL with -lscs or -lscs_mp, the default integer size is
     4 bytes (32 bits). Another version of SCSL is available in which integers
     are 8 bytes (64 bits).  This version allows the user access to larger
     memory sizes and helps when porting legacy Cray codes.  It can be loaded
     by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
     only one of the two versions; 4-byte integer and 8-byte integer library
     calls cannot be mixed.

     The C and C++ prototypes shown above are appropriate for the 4-byte
     integer version of SCSL. When using the 8-byte integer version, the
     variables of type int become long long and the <scsl_blas_i8.h> header
     file should be included.

DESCRIPTION
     SASUM and DASUM sum the absolute values of the elements of a real vector,
     as follows:

                           n
          sum <- ||x||  = Sum |x |
                      1   i=1   i


     where x is a real vector of length n.

     SCASUM and DZASUM sum the absolute values of the real and imaginary parts
     of the elements of a complex vector, as follows:

          sum <- ||Real(x)||  + Imag(x)|| =
                            1            1

                   n                n
                  Sum |Real(x )| + Sum |Imag(x )|
                  i=1        i     j=1        j


     where x is a complex vector of length n.

     For C/C++ arrays, the indices are from 0 to n-1.

     See the NOTES section of this man page for information about the
     interpretation of the data types described in the following arguments.

     These functions have the following arguments:

     sum       Sum of values.
               SASUM: Real sum of the absolute values of the elements of x.
               DASUM: Double precision sum of the absolute values of the
               elements of x.
               SCASUM: Real sum of the absolute values of the real and
               imaginary parts of the elements of x.
               DZASUM: Double precision sum of the absolute values of the real
               and imaginary parts of the elements of x.

     n         Integer.  (input)
               Number of elements in the vector to be summed.  If n <= 0,
               these routines return 0.

     x         Array of dimension (n-1) * |incx| + 1. (input)
               SASUM: Single precision array.
               DASUM: Double precision array.
               SCASUM: Single precision complex array.
               DZASUM:  Double precision complex array.

               Array x contains the vector to be summed.

     incx      Integer.  (input)
               Increment between elements of x.  If incx = 0, the results will
               be unpredictable.

NOTES
     These routines are Level 1 Basic Linear Algebra Subprograms (Level 1
     BLAS).

     When working backward (incx < 0), each routine starts at the end of the
     vector and moves backward, as follows:

     Fortran:

          x(1-incx *(n-1)), x(1incx * (n-2)), ... , x(1)


     C/C++:

          x(1-incx * (n-2)), x(1-incx * (n-3)), ..., x(0)


   Data Types
     The following data types are described in this documentation:
          Term Used                     Data type

     Fortran:

          Array dimensioned n           x(n)

          Character                     CHARACTER

          Integer                       INTEGER (INTEGER*8 for -lscs_i8[_mp])

          Single precision              REAL

          Double precision              DOUBLE PRECISION

          Single precision complex      COMPLEX

          Double precision complex      DOUBLE COMPLEX

     C/C++:

          Array dimensioned n           x[n]

          Character                     char

          Integer                       int (long long for -lscs_i8[_mp])

          Single precision              float

          Double precision              double

          Single precision complex      scsl_complex

          Double precision complex      scsl_zomplex

     C++ STL:

          Array dimensioned n           x[n]

          Character                     char

          Integer                       int (long long for -lscs_i8[_mp])

          Single precision              float

          Double precision              double

          Single precision complex      complex<float>

          Double precision complex      complex<double>

SEE ALSO
     INTRO_SCSL(3S), INTRO_BLAS1(3S)

     INTRO_CBLAS(3S) for information about using the C interface to Fortran 77
     Basic Linear Algebra Subprograms (legacy BLAS) set forth by the Basic
     Linear Algebra Subprograms Technical Forum.