/*  -- translated by f2c (version 20191129).

   You must link the resulting object file with libf2c:

  on Microsoft Windows system, link with libf2c.lib;

  on Linux or Unix systems, link with .../path/to/libf2c.a -lm

  or, if you install libf2c.a in a standard place, with -lf2c -lm

  -- in that order, at the end of the command line, as in

    cc *.o -lf2c -lm

  Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,

    http://www.netlib.org/f2c/libf2c.zip

*/

#include "f2c.h"

/* > \brief \b DDOT   

    =========== DOCUMENTATION ===========   

   Online html documentation available at   

              http://www.netlib.org/lapack/explore-html/   

    Definition:   

    ===========   

         DOUBLE PRECISION FUNCTION DDOT(N,DX,INCX,DY,INCY)   

         INTEGER INCX,INCY,N   

         DOUBLE PRECISION DX(*),DY(*)   

   > \par Purpose:   

    =============   

   >   

   > \verbatim   

   >   

   >    DDOT forms the dot product of two vectors.   

   >    uses unrolled loops for increments equal to one.   

   > \endverbatim   

    Arguments:   

    ==========   

   > \param[in] N   

   > \verbatim   

   >          N is INTEGER   

   >         number of elements in input vector(s)   

   > \endverbatim   

   >   

   > \param[in] DX   

   > \verbatim   

   >          DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) )   

   > \endverbatim   

   >   

   > \param[in] INCX   

   > \verbatim   

   >          INCX is INTEGER   

   >         storage spacing between elements of DX   

   > \endverbatim   

   >   

   > \param[in] DY   

   > \verbatim   

   >          DY is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCY ) )   

   > \endverbatim   

   >   

   > \param[in] INCY   

   > \verbatim   

   >          INCY is INTEGER   

   >         storage spacing between elements of DY   

   > \endverbatim   

    Authors:   

    ========   

   > \author Univ. of Tennessee   

   > \author Univ. of California Berkeley   

   > \author Univ. of Colorado Denver   

   > \author NAG Ltd.   

   > \date November 2017   

   > \ingroup double_blas_level1   

   > \par Further Details:   

    =====================   

   >   

   > \verbatim   

   >   

   >     jack dongarra, linpack, 3/11/78.   

   >     modified 12/3/93, array(1) declarations changed to array(*)   

   > \endverbatim   

   >   

    ===================================================================== */

doublereal igraphddot_(integer *n, doublereal *dx, integer *incx, doublereal *dy, 

  integer *incy)

{

    /* System generated locals */

    integer i__1;

    doublereal ret_val;

    /* Local variables */

    integer i__, m, ix, iy, mp1;

    doublereal dtemp;

/*  -- Reference BLAS level1 routine (version 3.8.0) --   

    -- Reference BLAS is a software package provided by Univ. of Tennessee,    --   

    -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--   

       November 2017   

    =====================================================================   

       Parameter adjustments */

    --dy;

    --dx;

    /* Function Body */

    ret_val = 0.;

    dtemp = 0.;

    if (*n <= 0) {

  return ret_val;

    }

    if (*incx == 1 && *incy == 1) {

/*        code for both increments equal to 1   

          clean-up loop */

  m = *n % 5;

  if (m != 0) {

      i__1 = m;

      for (i__ = 1; i__ <= i__1; ++i__) {

    dtemp += dx[i__] * dy[i__];

      }

      if (*n < 5) {

    ret_val = dtemp;

    return ret_val;

      }

  }

  mp1 = m + 1;

  i__1 = *n;

  for (i__ = mp1; i__ <= i__1; i__ += 5) {

      dtemp = dtemp + dx[i__] * dy[i__] + dx[i__ + 1] * dy[i__ + 1] + 

        dx[i__ + 2] * dy[i__ + 2] + dx[i__ + 3] * dy[i__ + 3] + 

        dx[i__ + 4] * dy[i__ + 4];

  }

    } else {

/*        code for unequal increments or equal increments   

            not equal to 1 */

  ix = 1;

  iy = 1;

  if (*incx < 0) {

      ix = (-(*n) + 1) * *incx + 1;

  }

  if (*incy < 0) {

      iy = (-(*n) + 1) * *incy + 1;

  }

  i__1 = *n;

  for (i__ = 1; i__ <= i__1; ++i__) {

      dtemp += dx[ix] * dy[iy];

      ix += *incx;

      iy += *incy;

  }

    }

    ret_val = dtemp;

    return ret_val;

} /* igraphddot_ */