X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=moebius2.git;a=blobdiff_plain;f=energy.c;h=9887ccb394fe1c09825287758599655ae2649430;hp=139e7e1304d11937fe5d5261e6dba81d9ad55c3e;hb=7aae3c873a9e339b52a1b1ef220035d2445d9a88;hpb=2c2c1cc2745430048709dc3b11aef7071d802c86

diff --git a/energy.c b/energy.c
index 139e7e1..9887ccb 100644
--- a/energy.c
+++ b/energy.c
@@ -6,75 +6,76 @@
 #include "bgl.h"
 #include "mgraph.h"
 
-#define BEST_F "best"
-#define INITIAL_F "initial"
+#include <gsl/gsl_errno.h>
+#include <gsl/gsl_multimin.h>
 
-static double edgewise_vertex_displacement_cost(const Vertices vertices);
-static double noncircular_rim_cost(Vertices vertices);
+static const char *input_file, *output_file;
+static char *output_file_tmp;
 
 static void compute_vertex_areas(const Vertices vertices, double areas[N]);
 static double best_energy= DBL_MAX;
-static void flushoutput(void);
 
-static void cost(double *energy, double tweight, double tcost);
-#define COST(weight, compute) cost(&energy, (weight), (compute))
+static void addcost(double *energy, double tweight, double tcost);
+#define COST(weight, compute) addcost(&energy, (weight), (compute))
 
 /*---------- main energy computation and subroutines ----------*/
 
-static double compute_energy(Vertices vertices) {
+static double compute_energy(const Vertices vertices) {
   double vertex_areas[N], energy;
 
   compute_vertex_areas(vertices,vertex_areas);
   energy= 0;
   printf("cost > energy |");
 
-  COST(1000.0, edgewise_vertex_displacement_cost(vertices));
-  COST(1.0,    graph_layout_cost(vertices,vertex_areas));
-  COST(1e3,    noncircular_rim_cost(vertices));
-  
+  COST(1e4, edgewise_vertex_displacement_cost(vertices));
+  COST(1e2, graph_layout_cost(vertices,vertex_areas));
+//  COST(1e4, noncircular_rim_cost(vertices));
+
   printf("| total %# e |", energy);
   if (energy < best_energy) {
-    FILE *best;
+    FILE *best_f;
+    int r;
+
     printf(" BEST");
-    
-    best_f= fopen(BEST_F ".new","wb");  if (!best_f) diee("fopen new best");
-    r= fwrite(vertices,sizeof(vertices),1,best_f); if (r!=1) diee("fwrite");
+
+    best_f= fopen(output_file_tmp,"wb");  if (!best_f) diee("fopen new out");
+    r= fwrite(vertices,sizeof(Vertices),1,best_f); if (r!=1) diee("fwrite");
     if (fclose(best_f)) diee("fclose new best");
-    if (rename(BEST_F ".new", BEST_F)) diee("rename install new best");
+    if (rename(output_file_tmp,output_file)) diee("rename install new best");
+
+    best_energy= energy;
   }
   putchar('\n');
   flushoutput();
 
   return energy;
-}    
+}
 
-static void cost(double *energy, double tweight, double tcost) {
+static void addcost(double *energy, double tweight, double tcost) {
   double tenergy= tweight * tcost;
   printf(" %# e > %# e |", tcost, tenergy);
   *energy += tenergy;
 }
 
-static void flushoutput(void) {
-  if (fflush(stdout) || ferror(stdout)) { perror("stdout"); exit(-1); }
-}
-
 static void compute_vertex_areas(const Vertices vertices, double areas[N]) {
+  int v0,v1,v2, e1,e2, k;
+
   FOR_VERTEX(v0) {
     double total= 0.0;
     int count= 0;
-    
+
     FOR_VEDGE(v0,e1,v1) {
       e2= (e1+1) % V6;
       v2= EDGE_END2(v0,e2);
       if (v2<0) continue;
-      
+
       double e1v[D3], e2v[D3], av[D3];
       K {
 	e1v[k]= vertices[v1][k] - vertices[v0][k];
 	e2v[k]= vertices[v2][k] - vertices[v0][k];
       }
       xprod(av, e1v, e2v);
-      total += hypotD1(av);
+      total += magnD(av);
       count++;
     }
     areas[v0]= total / count;
@@ -101,38 +102,36 @@ static void compute_vertex_areas(const Vertices vertices, double areas[N]) {
    * In our application we are searching for the optimal locations of
    * N actualvertices in D3 (3) dimensions - ie, we are searching for
    * the optimal metapoint in an N*D3-dimensional space.
-   * 
+   *
    * So eg with X=Y=100, the simplex will contain 300 metavertices
    * each of which is an array of 300 doubles for the actualvertex
    * coordinates.  Hopefully this won't be too slow ...
    */
 
-static void gsldie(const char *what, int status) {
-  fprintf(stderr,"gsl function failed: %s: %s\n", what, gsl_strerror(status));
-  exit(-1);
-}
-
 static gsl_multimin_fminimizer *minimiser;
 
-static const stop_epsilon= 1e-4;
-
-#define DIM (N*D3)
+static const double stop_epsilon= 1e-4;
 
 static double minfunc_f(const gsl_vector *x, void *params) {
   assert(x->size == DIM);
   assert(x->stride == 1);
-  return compute_energy((Vertices)x->data);
+  return compute_energy((const double(*)[D3])x->data);
 }
 
 int main(int argc, const char *const *argv) {
-  struct gsl_multimin_function multimin_function;
+  gsl_multimin_function multimin_function;
   double size;
   Vertices initial, step_size;
-  FILE *initial;
+  FILE *initial_f;
   gsl_vector initial_gsl, step_size_gsl;
-  int r;
-  
-  if (argc>1) { fputs("takes no arguments\n",stderr); exit(8); }
+  int r, v, k;
+
+  if (argc!=3 || argv[1][0]=='-' || strncmp(argv[2],"-o",2))
+    { fputs("usage: minimise <input> -o<output\n",stderr); exit(8); }
+
+  input_file= argv[1];
+  output_file= argv[2]+2;
+  if (asprintf(&output_file_tmp,"%s.new",output_file) <= 0) diee("asprintf");
 
   minimiser= gsl_multimin_fminimizer_alloc
     (gsl_multimin_fminimizer_nmsimplex, DIM);
@@ -142,7 +141,7 @@ int main(int argc, const char *const *argv) {
   multimin_function.n= DIM;
   multimin_function.params= 0;
 
-  initial_f= fopen(INITIAL_F,"rb");  if (!initial_f) diee("fopen initial");
+  initial_f= fopen(input_file,"rb");  if (!initial_f) diee("fopen initial");
   errno= 0; r= fread(initial,sizeof(initial),1,initial_f);
   if (r!=1) diee("fread");
   fclose(initial_f);
@@ -153,138 +152,104 @@ int main(int argc, const char *const *argv) {
   initial_gsl.owner= 0;
   step_size_gsl= initial_gsl;
 
-  initial_gsl.data= initial;
-  step_size_gsl.data= step_size;
+  initial_gsl.data= &initial[0][0];
+  step_size_gsl.data= &step_size[0][0];
 
   FOR_VERTEX(v)
-    K step_size[v][k]= 1e-3;
-  FOR_RIM_VERTEX(vx,vy,v)
-    step_size[v][3] *= 0.1;
-  
-  for (vy=0; vy<Y; vy+=Y-1)
-  for (vx=0; vx<x
-  for (i=0; i<DIM; i++) step_size[i]= step_size;
-  
-
-  step_size= gsl_vector_alloc(DIM);  if (!step_size) gsldie("alloc step");
-  gsl_vector_set_all(step_size, 1e-3);
-
-  assert(step_
-  step_
-
-  r= gsl_multimin_fminimizer_set(minimiser, &multimin_function,
-				 &initial_gsl, &step_size);
-  if (r) { gsldie("fminimizer_set",r); }
-  
+    K step_size[v][k]= 0.03;
+//int vx,vy;
+//  FOR_RIM_VERTEX(vx,vy,v)
+//    step_size[v][3] *= 0.1;
+
+  GA( gsl_multimin_fminimizer_set(minimiser, &multimin_function,
+				  &initial_gsl, &step_size_gsl) );
+
   for (;;) {
-    r= gsl_multimin_fminimizer_iterate(minimiser);
-    if (r) { gsldie("fminimizer_iterate",r); }
+    GA( gsl_multimin_fminimizer_iterate(minimiser) );
 
     size= gsl_multimin_fminimizer_size(minimiser);
     r= gsl_multimin_test_size(size, stop_epsilon);
 
-    printf("size %# e, r=%d\n", size, r);
+    printf("%*s size %# e, r=%d\n", 135,"", size, r);
     flushoutput();
 
     if (r==GSL_SUCCESS) break;
     assert(r==GSL_CONTINUE);
   }
+  return 0;
 }
 
 /*---------- Edgewise vertex displacement ----------*/
 
   /*
-   *  
+   *
    *
    *
    *   	            Q `-_
    *              / |    `-_
-   *   R' - _ _ _/_ |       `-.
-   *    .       /   M - - - - - S
-   *    .      /    |      _,-'
-   *    .     /     |  _,-'
-   *    .    /    , P '
-   *    .   /  ,-'
-   *    .  /,-'
-   *    . /'
+   *             /  |       `-.
+   *            /   M - - - - - S
+   *           /  ' |      _,-'
+   *          /  '  |  _,-'
+   *         / '  , P '
+   *        / ',-'
+   *       /,-'
+   *      /'
    *   	 R
    *
+   *  Let delta =  180deg - angle RMS
    *
-   *
-   *  Find R', the `expected' location of R, by
-   *  reflecting S in M (the midpoint of QP).
-   *
-   *  Let 2d = |RR'|
-   *       b = |PQ|
-   *       l = |RS|
+   *  Let  l = |PQ|
+   *       d = |RS|
    *
    *  Giving energy contribution:
    *
-   *                               2
-   *                            b d
-   *    E             =  F   .  ----
-   *     vd, edge PQ      vd      3
-   *                             l
+   *                                   2
+   *                            l delta
+   *    E             =  F   .  --------
+   *     vd, edge PQ      vd       d
    *
-   *  (The dimensions of this are those of F_vd.)
    *
-   *  By symmetry, this calculation gives the same answer with R and S
-   *  exchanged.  Looking at the projection in the RMS plane:
-   *
-   *
-   *	       	       	       S'
-   *	   	    	     ,'
-   *	       	       	   ,'
-   *   	R'           	 ,'    	       	2d" = |SS'| = |RR'| = 2d
-   *	  `-._         ,'
-   *   	      `-._   ,'	      		By congruent triangles,
-   *              ` M	      		with M' = midpoint of RS,
-   *	       	  ,'  `-._     	       	|MM'| = |RR'|/2 = d
-   *	       	,'     	  `-._
-   *	      ,'       	      ` S       So use
-   *	    ,'	     M' _ , - '            d = |MM'|
-   *	  ,'   _ , - '
-   *	 R - '
+   *  (The dimensions of this are those of F_vd.)
    *
-   *  We choose this value for l (rather than |RM|+|MS|, say, or |RM|)
-   *  because we want this symmetry and because we're happy to punish
-   *  bending more than uneveness in the metric.
+   *  We calculate delta as  atan2(|AxB|, A.B)
+   *  where A = RM, B = MS
    *
-   *  In practice to avoid division by zero we'll add epsilon to l^3
-   *  and the huge energy ought then to be sufficient for the model to
-   *  avoid being close to R=S.
+   *  In practice to avoid division by zero we'll add epsilon to d and
+   *  |AxB| and the huge energy ought then to be sufficient for the
+   *  model to avoid being close to R=S.
    */
 
-static double edgewise_vertex_displacement_cost(const Vertices vertices) {
-  static const l3_epsison= 1e-6;
+double edgewise_vertex_displacement_cost(const Vertices vertices) {
+  static const double axb_epsilon= 1e-6;
 
   int pi,e,qi,ri,si, k;
-  double m[D3], mprime[D3], b, d2, l, sigma_bd2_l3;
+  double m[D3], a[D3], b[D3], axb[D3];
+  double total_cost= 0;
 
   FOR_EDGE(pi,e,qi) {
-    ri= EDGE_END2(pi,(e+1)%V6); if (r<0) continue;
-    si= EDGE_END2(pi,(e+5)%V6); if (s<0) continue;
-    assert(ri == EDGE_END2(qi,(e+2)%V6));
-    assert(si == EDGE_END2(qi,(e+4)%V6));
-    
+    ri= EDGE_END2(pi,(e+1)%V6); if (ri<0) continue;
+    si= EDGE_END2(pi,(e+5)%V6); if (si<0) continue;
+
     K m[k]= (vertices[pi][k] + vertices[qi][k]) * 0.5;
-    K mprime[k]= (vertices[ri][k] + vertices[si][k]) * 0.5;
-    b= hypotD(vertices[pi], vertices[qi]);
-    d2= hypotD2(m, mprime);
-    l= hypotD(vertices[ri][k] - vertices[si][k]);
-    l3 = l*l*l + l3_epsilon;
+    K a[k]= -vertices[ri][k] + m[k];
+    K b[k]= -m[k] + vertices[si][k];
 
-    sigma_bd2_l3 += b * d2 / l3;
+    xprod(axb,a,b);
+    
+    double delta= atan2(magnD(axb) + axb_epsilon, dotprod(a,b));
+    double cost= delta * delta;
+    total_cost += cost;
   }
-  return sigma_bd2_l3;
+  return total_cost;
 }
 
 /*---------- noncircular rim cost ----------*/
 
-static double noncircular_rim_cost(Vertices vertices) {
+double noncircular_rim_cost(const Vertices vertices) {
   int vy,vx,v;
   double cost= 0.0;
-  
+
   FOR_RIM_VERTEX(vy,vx,v) {
     double oncircle[3];
     /* By symmetry, nearest point on circle is the one with
@@ -298,4 +263,5 @@ static double noncircular_rim_cost(Vertices vertices) {
     double d2= hypotD2(vertices[v], oncircle);
     cost += d2*d2;
   }
+  return cost;
 }