sdot(3S)

NAME
     SDOT, DDOT, CDOTC, ZDOTC, CDOTU, ZDOTU - Computes a dot product (inner
     product) of two real or complex vectors

SYNOPSIS
     Single precision

          Fortran:
               real SDOT
               real dot
               dot = SDOT (n, x, incx, y, incy)

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

     Double precision

          Fortran:
               double precision DDOT
               double precision dot
               dot = DDOT (n, x, incx, y, incy)

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

     Single precision complex

          Fortran:
               complex CDOTC CDOTU
               complex dot
               dot = CDOTC (n, x, incx, y, incy)
               dot = CDOTU (n, x, incx, y, incy)

          C/C++:
               #include <scsl_blas.h>
               scsl_complex cdotc(int n, scsl_complex *x, int incx,
               scsl_complex *y, int incy);
               scsl_complex cdotu(int n, scsl_complex *x, int incx,
               scsl_complex *y, int incy);

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

     Double precision complex

          Fortran:
               double complex ZDOTC ZDOTU
               double complex dot
               dot = ZDOTC (n, x, incx, y, incy)
               dot = ZDOTU (n, x, incx, y, incy)
          C/C++:
               #include <scsl_blas.h>
               scsl_zomplex zdotc(int n, scsl_zomplex *x, int incx,
               scsl_zomplex *y, int incy);
               scsl_zomplex zdotu(int n, scsl_zomplex *x, int incx,
               scsl_zomplex *y, int incy);

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

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
     SDOT/DDOT computes a dot product of two real vectors (l2 real inner
     product).

     CDOTC/ZDOTC computes a dot product of the conjugate of a complex vector
     and another complex vector (l2 complex inner product).

     CDOTU/ZDOTU computes a dot product of two complex vectors.

     SDOT/DDOT and CDOTU/ZDOTU perform the following vector operation:
                  T      n
          dot <- x  y = Sum x  y
                        i=1  i  i


     where x and y are real or complex vectors, and xT is the transpose of x.

     CDOTC/ZDOTC performs the following vector operation:

                  H      n   _
          dot <- x  y = Sum  x  y
                        i=1   i  i


     where x and y are complex vectors, and xH is the conjugate transpose of
     x.

     If n <= 0, dot is set to 0.

     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:

     n    Integer.  (input)
          Number of elements in each vector.

     x    Array of dimension (n-1) * |incx| + 1.  (input)
          SDOT: Single precision array.
          DDOT: Double precision array.
          CDOTC, CDOTU: Single precision complex array.
          ZDOTC, CDOTU: Double precision complex array.
          Array x contains the first vector operand.

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

     y    Array of dimension (n-1)  * |incy| + 1.  (input)
          SDOT: Single precision array.
          DDOT: Double precision array.
          CDOTC, CDOTU: Single precision complex array.
          ZDOTC, ZDOTU: Double precision complex array.
          Array y contains the second vector operand.

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

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

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

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

          y(1-incy * (n-1)), y(1-incy * (n-2)), ..., y(1)


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

          Term Used                     Data type

     Fortran:

          Array dimensioned n           x(n)

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

          Character                     CHARACTER

          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.