5 /* We want to do multidimensional minimisation.
7 * We don't think there are any local minima. Or at least, if there
8 * are, the local minimum which will be found from the starting
9 * state is the one we want.
11 * We don't want to try to provide a derivative of the cost
12 * function. That's too tedious (and anyway the polynomial
13 * approximation to our our cost function sometimes has high degree
14 * in the inputs which means the quadratic model implied by most of
15 * the gradient descent minimisers is not ideal).
17 * This eliminates most of the algorithms. Nelder and Mead's
18 * simplex algorithm is still available and we will try that.
20 * In our application we are searching for the optimal locations of
21 * N actualvertices in D3 (3) dimensions - ie, we are searching for
22 * the optimal metapoint in an N*D3-dimensional space.
24 * So eg with X=Y=100, the simplex will contain 300 metavertices
25 * each of which is an array of 300 doubles for the actualvertex
26 * coordinates. Hopefully this won't be too slow ...
31 #include <gsl/gsl_errno.h>
32 #include <gsl/gsl_multimin.h>
40 const char *input_file, *output_file;
41 char *output_file_tmp;
43 static void printing_init(void);
45 static gsl_multimin_fminimizer *minimiser;
47 static const double stop_epsilon= 1e-6;
49 static double minfunc_f(const gsl_vector *x, void *params) {
52 assert(x->size == DIM);
53 assert(x->stride == 1);
54 map_dimensions(x->data, vs.a);
55 return compute_energy(&vs);
58 int main(int argc, const char *const *argv) {
59 gsl_multimin_function multimin_function;
61 struct Vertices initial_full;
62 double initial_half[DIM], step_size[DIM];
64 gsl_vector initial_gsl, step_size_gsl;
67 if (argc!=3 || argv[1][0]=='-' || strncmp(argv[2],"-o",2))
68 { fputs("usage: minimise <input> -o<output\n",stderr); exit(8); }
71 output_file= argv[2]+2;
72 if (asprintf(&output_file_tmp,"%s.new",output_file) <= 0) diee("asprintf");
74 graph_layout_prepare();
78 printf("X=%d=0x%x Y=%d=0x%x DIM=%d\n",X,X,Y,Y,DIM);
80 minimiser= gsl_multimin_fminimizer_alloc
81 (gsl_multimin_fminimizer_nmsimplex, DIM);
82 if (!minimiser) { perror("alloc minimiser"); exit(-1); }
84 multimin_function.f= minfunc_f;
85 multimin_function.n= DIM;
86 multimin_function.params= 0;
88 initial_f= fopen(input_file,"rb"); if (!initial_f) diee("fopen initial");
89 errno= 0; r= fread(&initial_full,sizeof(initial_full),1,initial_f);
90 if (r!=1) diee("fread");
93 pmap_dimensions(&initial_full);
94 unmap_dimensions(initial_half,&initial_full);
95 for (i=0; i<DIM; i++) step_size[i]= 0.03;
97 initial_gsl.size= DIM;
98 initial_gsl.stride= 1;
100 initial_gsl.owner= 0;
101 step_size_gsl= initial_gsl;
103 initial_gsl.data= initial_half;
104 step_size_gsl.data= step_size;
106 GA( gsl_multimin_fminimizer_set(minimiser, &multimin_function,
107 &initial_gsl, &step_size_gsl) );
110 GA( gsl_multimin_fminimizer_iterate(minimiser) );
112 size= gsl_multimin_fminimizer_size(minimiser);
113 r= gsl_multimin_test_size(size, stop_epsilon);
115 if (printing_check(pr_size,155))
116 printf("size %# e, r=%d\n", size, r);
119 if (r==GSL_SUCCESS) break;
120 assert(r==GSL_CONTINUE);
125 /*---------- printing rate limit ----------*/
127 static volatile unsigned print_todo;
128 static sigset_t print_alarmset;
130 int printing_check(enum printing_instance which, int indent) {
131 static int skipped[pr__max];
133 unsigned bits= 1u << which;
136 if (!(print_todo & bits)) {
141 sigprocmask(SIG_BLOCK,&print_alarmset,0);
143 sigprocmask(SIG_UNBLOCK,&print_alarmset,0);
146 if (sk) printf("%*s[%4d] ",indent,"", sk);
153 static void alarmhandler(int ignored) {
157 static void printing_init(void) {
159 struct itimerval itv;
161 sigemptyset(&print_alarmset);
162 sigaddset(&print_alarmset,SIGALRM);
164 sa.sa_handler= alarmhandler;
165 sa.sa_mask= print_alarmset;
166 sa.sa_flags= SA_RESTART;
167 if (sigaction(SIGALRM,&sa,0)) diee("sigaction ALRM");
169 itv.it_interval.tv_sec= 0;
170 itv.it_interval.tv_usec= 200000;
171 itv.it_value= itv.it_interval;
173 if (setitimer(ITIMER_REAL,&itv,0)) diee("setitimer REAL");