util.c

/*
 * Copyright 1997, Regents of the University of Minnesota
 *
 * util.c
 *
 * This function contains various utility routines
 *
 * Started 9/28/95
 * George
 *
 * $Id: util.c 10495 2011-07-06 16:04:45Z karypis $
 */

#include "metislib.h"


/*************************************************************************/
/*! This function initializes the random number generator 
  */
/*************************************************************************/
void InitRandom(idx_t seed)
{
  isrand((seed == -1 ? 4321 : seed)); 
}


/*************************************************************************/
/*! Returns the highest weight index of x[i]*y[i] 
 */
/*************************************************************************/
idx_t iargmax_nrm(size_t n, idx_t *x, real_t *y)
{
  idx_t i, max=0;
      
  for (i=1; i<n; i++)
     max = (x[i]*y[i] > x[max]*y[max] ? i : max);
                
  return max;
}


/*************************************************************************/
/*! These functions return the index of the maximum element in a vector
  */
/*************************************************************************/
idx_t iargmax_strd(size_t n, idx_t *x, idx_t incx)
{
  size_t i, max=0;

  n *= incx;
  for (i=incx; i<n; i+=incx)
    max = (x[i] > x[max] ? i : max);

  return max/incx;
}


/*************************************************************************/
/*! These functions return the index of the almost maximum element in a 
    vector
 */
/*************************************************************************/
idx_t rargmax2(size_t n, real_t *x)
{
  size_t i, max1, max2;

  if (x[0] > x[1]) {
    max1 = 0;
    max2 = 1;
  }
  else {
    max1 = 1;
    max2 = 0;
  }

  for (i=2; i<n; i++) {
    if (x[i] > x[max1]) {
      max2 = max1;
      max1 = i;
    }
    else if (x[i] > x[max2])
      max2 = i;
  }

  return max2;
}


/*************************************************************************/
/*! These functions return the index of the second largest elements in the
    vector formed by x.y where '.' is element-wise multiplication */
/*************************************************************************/
idx_t iargmax2_nrm(size_t n, idx_t *x, real_t *y)
{
  size_t i, max1, max2;

  if (x[0]*y[0] > x[1]*y[1]) {
    max1 = 0;
    max2 = 1;
  }
  else {
    max1 = 1;
    max2 = 0;
  }

  for (i=2; i<n; i++) {
    if (x[i]*y[i] > x[max1]*y[max1]) {
      max2 = max1;
      max1 = i;
    }
    else if (x[i]*y[i] > x[max2]*y[max2])
      max2 = i;
  }

  return max2;
}


/*************************************************************************/
/*! converts a signal code into a Metis return code 
 */
/*************************************************************************/
int metis_rcode(int sigrval)
{
  switch (sigrval) {
    case 0:
      return METIS_OK;
      break;
    case SIGMEM:
      return METIS_ERROR_MEMORY;
      break;
    default:
      return METIS_ERROR;
      break;
  }
}