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, *best_file;
42 long long evaluations;
43 double stop_epsilon= 1e-20;
45 static void printing_init(void);
47 static gsl_multimin_fminimizer *minimiser;
48 static const char *final_file;
49 static char *final_file_tmp;
51 static double minfunc_f(const gsl_vector *x, void *params) {
54 assert(x->size == DIM);
55 assert(x->stride == 1);
56 map_dimensions(x->data, vs.a);
57 return compute_energy(&vs);
60 static void badusage(void) {
61 fputs("usage: minimise <input> [-i<intermediate>] -o<output\n",stderr);
65 static sig_atomic_t quit_requested;
67 static void sigint_handler(int ignored) {
71 int main(int argc, const char *const *argv) {
72 gsl_multimin_function multimin_function;
74 struct Vertices initial_full;
75 double initial_half[DIM], step_size[DIM];
77 gsl_vector initial_gsl, step_size_gsl;
78 int r, i, size_check_counter= 0;
83 if (strncmp(argv[2],"-o",2)) badusage(); best_file= argv[2]+2;
87 if (strncmp(argv[2],"-i",2)) badusage(); best_file= argv[2]+2;
88 if (strncmp(argv[3],"-o",2)) badusage(); final_file= argv[3]+2;
92 if (argv[1][0]=='-') badusage();
94 if (asprintf(&best_file_tmp,"%s.new",best_file) <= 0) diee("asprintf");
96 if (asprintf(&final_file_tmp,"%s.new",final_file) <= 0) diee("asprintf");
98 memset(&sa,0,sizeof(sa));
99 sa.sa_handler= sigint_handler;
100 sa.sa_flags= SA_RESETHAND;
101 r= sigaction(SIGINT,&sa,0);
102 if (r) diee("sigaction SIGINT");
105 graph_layout_prepare();
109 printf("X=%d=0x%x Y=%d=0x%x DIM=%d\n",X,X,Y,Y,DIM);
111 minimiser= gsl_multimin_fminimizer_alloc
112 (gsl_multimin_fminimizer_nmsimplex, DIM);
113 if (!minimiser) { perror("alloc minimiser"); exit(-1); }
115 multimin_function.f= minfunc_f;
116 multimin_function.n= DIM;
117 multimin_function.params= 0;
119 initial_f= fopen(input_file,"rb"); if (!initial_f) diee("fopen initial");
120 errno= 0; r= fread(&initial_full,sizeof(initial_full),1,initial_f);
121 if (r!=1) diee("fread");
124 pmap_dimensions(&initial_full);
125 unmap_dimensions(initial_half,&initial_full);
126 for (i=0; i<DIM; i++) step_size[i]= 0.03;
128 initial_gsl.size= DIM;
129 initial_gsl.stride= 1;
130 initial_gsl.block= 0;
131 initial_gsl.owner= 0;
132 step_size_gsl= initial_gsl;
134 initial_gsl.data= initial_half;
135 step_size_gsl.data= step_size;
137 GA( gsl_multimin_fminimizer_set(minimiser, &multimin_function,
138 &initial_gsl, &step_size_gsl) );
141 if (quit_requested) {
142 fprintf(stderr,"SIGINT caught.\n");
146 GA( gsl_multimin_fminimizer_iterate(minimiser) );
148 if (!(size_check_counter++ % DIM)) {
149 size= gsl_multimin_fminimizer_size(minimiser);
150 r= gsl_multimin_test_size(size, stop_epsilon);
152 if (printing_check(pr_size,215))
153 printf("r=%2d, size %# e\n", r, size);
156 if (r==GSL_SUCCESS) break;
157 assert(r==GSL_CONTINUE);
162 if (unlink(final_file_tmp) && errno != ENOENT) diee("unlink final .tmp");
163 if (link(best_file,final_file_tmp)) diee("link final .tmp");
164 if (rename(final_file_tmp,final_file)) diee("install final");
166 printf("FINISHED (%lld evaluations)\n",evaluations);
171 /*---------- printing rate limit ----------*/
173 static volatile unsigned print_todo;
174 static sigset_t print_alarmset;
176 int printing_check(enum printing_instance which, int indent) {
177 static int skipped[pr__max];
179 unsigned bits= 1u << which;
182 if (!(print_todo & bits)) {
187 sigprocmask(SIG_BLOCK,&print_alarmset,0);
189 sigprocmask(SIG_UNBLOCK,&print_alarmset,0);
191 printf("%*s",indent,"");
193 if (sk) printf("[%4d] ",sk);
200 static void alarmhandler(int ignored) {
204 static void printing_init(void) {
206 struct itimerval itv;
208 sigemptyset(&print_alarmset);
209 sigaddset(&print_alarmset,SIGALRM);
211 sa.sa_handler= alarmhandler;
212 sa.sa_mask= print_alarmset;
213 sa.sa_flags= SA_RESTART;
214 if (sigaction(SIGALRM,&sa,0)) diee("sigaction ALRM");
216 itv.it_interval.tv_sec= 0;
217 itv.it_interval.tv_usec= 200000;
218 itv.it_value= itv.it_interval;
220 if (setitimer(ITIMER_REAL,&itv,0)) diee("setitimer REAL");