• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

ddot - compute the dot product of two vectors x and y.

SYNOPSIS

  DOUBLE PRECISION FUNCTION DDOT( N, X, INCX, Y, INCY)
  INTEGER N, INCX, INCY
  DOUBLE PRECISION X(*), Y(*)

  DOUBLE PRECISION FUNCTION DDOT_64( N, X, INCX, Y, INCY)
  INTEGER*8 N, INCX, INCY
  DOUBLE PRECISION X(*), Y(*)

F95 INTERFACE

  REAL(8) FUNCTION DOT( [N], X, [INCX], Y, [INCY])
  INTEGER :: N, INCX, INCY
  REAL(8), DIMENSION(:) :: X, Y

  REAL(8) FUNCTION DOT_64( [N], X, [INCX], Y, [INCY])
  INTEGER(8) :: N, INCX, INCY
  REAL(8), DIMENSION(:) :: X, Y

C INTERFACE

#include <sunperf.h>

double ddot(int n, double *x, int incx, double *y, int incy);

double ddot_64(long n, double *x, long incx, double *y, long incy);

PURPOSE

ddot compute the dot product of x and y where x and y are n-vectors.

ARGUMENTS

• N (input)
  On entry, N specifies the number of elements in the vector. If N is not positive then the function returns the value 0.0. Unchanged on exit.

• X (input)
  ( 1 + ( n - 1 )*abs( INCX ) ). On entry, the incremented array X must contain the vector x. Unchanged on exit.

• INCX (input)
  On entry, INCX specifies the increment for the elements of X. INCX must not be zero. Unchanged on exit.

• Y (input)
  ( 1 + ( n - 1 )*abs( INCY ) ). On entry, the incremented array Y must contain the vector y. Unchanged on exit.

• INCY (input)
  On entry, INCY specifies the increment for the elements of Y. INCY must not be zero. Unchanged on exit.