C++ (Cpp) logfac Examples

Example #1

File: vsubs.c Project: razibkkhan/eigensoft

double logbino(int n, int k)
/* log n choose k */
{
    double top, bot ;

    top = logfac(n) ;
    bot = logfac(n-k) + logfac(k) ;

    return top-bot ;
}

Example #2

// calculate the weights for the hermite polynomial
// at the roots
// using formula Abramowitz and Stegun chapter 25.4.46 p.890
void hermite_weight(long n, double * hroot, double * weights)
{
  long i;
  double hr2;
  double nominator = exp(LOG2 * ( n-1.) + logfac(n)) * SQRTPI / (n*n);
  for(i=0;i<n; i++)
    {
      hr2 = hermite(n-1, hroot[i]);
      weights[i] = nominator / (hr2*hr2);
    }
}

Example #3

File: laguerre.c Project: mipearson/migrate-n

// calculate the weights for the hermite polynomial
// at the roots
// using formula Abramowitz and Stegun chapter 25.4.46 p.890
void
hermite_weight (long n, MYREAL *hroot, MYREAL *weights)
{
    long i;
    MYREAL hr2;
    MYREAL nominator = EXP (LOG2 * (n - 1.) + logfac (n)) * SQRTPI / (n * n);
    for (i = 0; i < n; i++)
    {
        hr2 = hermite (n - 1, hroot[i]);
        weights[i] = nominator / (hr2 * hr2);
    }
}