int gauss(dvec& x, dvec& w) {
int n = x.size();
double dist = 1;
double tol = 1e-15;
int iter = 0;
// Use Chebyshev-Gauss nodes and initial guess
initguess(x);
// chebnodes(x);
dvec x0(x);
dvec L(n,0.0);
dvec Lp(n,0.0);
dvec a(n,0.0);
dvec b(n,0.0);
rec_legendre(a,b);
// Iteratively correct nodes with Newton's method
while(dist>tol) {
newton_step(a,b,x,L,Lp);
dist = dist_max(x,x0);
++iter;
x0 = x;
}
// Compute Weights
for(int i=0;i<n;++i){
w[i] = 2.0/((1-x[i]*x[i])*(Lp[i]*Lp[i]));
}
return iter;
}
/*
* Routine: DistSizeToShiftWidth(char *szDist)
* Purpose: Determine the number of bits required to select a member of the distribution
* Algorithm:
* Data Structures:
*
* Params:
* Returns:
* Called By:
* Calls:
* Assumptions:
* Side Effects:
* TODO: None
*/
int DistSizeToShiftWidth(char *szDist, int nWeightSet)
{
int nBits = 1,
nTotal = 2,
nMax;
d_idx_t *d;
d = find_dist(szDist);
nMax = dist_max(d->dist, nWeightSet);
while (nTotal < nMax)
{
nBits += 1;
nTotal <<= 1;
}
return(nBits);
}
