/*	Grid.c		utility functions for the Vegas grid		this file is part of Vegas		last modified 2 Mar 06 th*/static inline void GetGrid(Grid *grid){  count bin, dim;  unsigned const int slot = EXPORT(vegasgridno) - 1;  if( slot < MAXGRIDS && gridptr_[slot] ) {    if( griddim_[slot] == ndim_ ) {      VecCopy(grid, gridptr_[slot]);      return;    }    free(gridptr_[slot]);    gridptr_[slot] = NULL;  }  for( bin = 0; bin < NBINS; ++bin )    grid[0][bin] = (bin + 1)/(real)NBINS;  for( dim = 1; dim < ndim_; ++dim )    Copy(&grid[dim], &grid[0], 1);}/*********************************************************************/static inline void PutGrid(Grid *grid){  unsigned const int slot = EXPORT(vegasgridno) - 1;  if( slot < MAXGRIDS ) {    if( gridptr_[slot] == NULL ) Alloc(gridptr_[slot], ndim_);    griddim_[slot] = ndim_;    VecCopy(gridptr_[slot], grid);  }}/*********************************************************************/static void RefineGrid(Grid grid, Grid margsum){  real avgperbin, thisbin;  Grid imp, newgrid;  int bin, newbin;  /* smooth the f^2 value stored for each bin */  real prev = margsum[0];  real cur = margsum[1];  real norm = margsum[0] = .5*(prev + cur);  for( bin = 1; bin < NBINS - 1; ++bin ) {    creal s = prev + cur;    prev = cur;    cur = margsum[bin + 1];    norm += margsum[bin] = (s + cur)/3.;  }  norm += margsum[NBINS - 1] = .5*(prev + cur);  if( norm == 0 ) return;  norm = 1/norm;  /* compute the importance function for each bin */  avgperbin = 0;  for( bin = 0; bin < NBINS; ++bin ) {    real impfun = 0;    if( margsum[bin] > 0 ) {      creal r = margsum[bin]*norm;      avgperbin += impfun = pow((r - 1)/log(r), 1.5);    }    imp[bin] = impfun;  }  avgperbin /= NBINS;  /* redefine the size of each bin */  cur = 0;  thisbin = 0;  bin = -1;  for( newbin = 0; newbin < NBINS - 1; ++newbin ) {    while( thisbin < avgperbin ) {      thisbin += imp[++bin];      prev = cur;      cur = grid[bin];    }    thisbin -= avgperbin;    newgrid[newbin] = cur - 2*(cur - prev)*thisbin/      (imp[bin] + imp[IDim(bin - 1)]);  }  Copy(grid, newgrid, NBINS - 1);  grid[NBINS - 1] = 1;}