src/delta_plot.c

   1 /* delta_plot.c       2011-06-23 */
   2
   3 /* Copyright 2010-2011 Emmanuel Paradis
   4
   5 /* This file is part of the R-package `ape'. */
   6 /* See the file ../COPYING for licensing issues. */
   7
   8 #include <R.h>
   9
  10 void delta_plot(double *D, int *size, int *nbins, int *counts, double *deltabar)
  11 {
  12         int x, y, u, v; /* same notation than in Holland et al. 2002 */
  13         int n = *size, nb = *nbins;
  14         double dxy, dxu, dxv, dyu, dyv, duv, A, B, C, delta;
  15         int xy, xu, xv, yu, yv, uv, i;
  16
  17         for (x = 0; x < n - 3; x++) {
  18                 xy = x*n - x*(x + 1)/2; /* do NOT factorize */
  19                 for (y = x + 1; y < n - 2; y++, xy++) {
  20                         yu = y*n - y*(y + 1)/2; /* do NOT factorize */
  21                         dxy = D[xy];
  22                         xu = xy + 1;
  23                         for (u = y + 1; u < n - 1; u++, xu++, yu++) {
  24                                 uv = u*n - u*(u + 1)/2; /* do NOT factorize */
  25                                 dxu = D[xu]; dyu = D[yu];
  26                                 xv = xu + 1; yv = yu + 1;
  27                                 for (v = u + 1; v < n; v++, xv++, yv++, uv++) {
  28                                         dxv = D[xv]; dyv = D[yv]; duv = D[uv];
  29                                         A = dxv + dyu; B = dxu + dyv; C = dxy + duv;
  30                                         if (A == B && B == C) delta = 0; else while (1) {
  31                                                 if (C <= B && B <= A) {delta = (A - B)/(A - C); break;}
  32                                                 if (B <= C && C <= A) {delta = (A - C)/(A - B); break;}
  33                                                 if (A <= C && C <= B) {delta = (B - C)/(B - A); break;}
  34                                                 if (C <= A && A <= B) {delta = (B - A)/(B - C); break;}
  35                                                 if (A <= B && B <= C) {delta = (C - B)/(C - A); break;}
  36                                                 if (B <= A && A <= C) {delta = (C - A)/(C - B); break;}
  37                                         }
  38                                         /* if (delta == 1) i = nb - 1; else */
  39                                         i = delta * nb;
  40                                         counts[i] += 1;
  41                                         deltabar[x] += delta;
  42                                         deltabar[y] += delta;
  43                                         deltabar[u] += delta;
  44                                         deltabar[v] += delta;
  45                                 }
  46                         }
  47                 }
  48         }
  49 }