--- /dev/null
+/*
+ * use of GSL
+ */
+
+ /* We want to do multidimensional minimisation.
+ *
+ * We don't think there are any local minima. Or at least, if there
+ * are, the local minimum which will be found from the starting
+ * state is the one we want.
+ *
+ * We don't want to try to provide a derivative of the cost
+ * function. That's too tedious (and anyway the polynomial
+ * approximation to our our cost function sometimes has high degree
+ * in the inputs which means the quadratic model implied by most of
+ * the gradient descent minimisers is not ideal).
+ *
+ * This eliminates most of the algorithms. Nelder and Mead's
+ * simplex algorithm is still available and we will try that.
+ *
+ * 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 ...
+ */
+
+#include "common.h"
+
+#include <gsl/gsl_errno.h>
+#include <gsl/gsl_multimin.h>
+
+#include <signal.h>
+#include <sys/time.h>
+
+#include "half.h"
+#include "minimise.h"
+
+const char *input_file, *output_file;
+char *output_file_tmp;
+
+static void printing_init(void);
+
+static gsl_multimin_fminimizer *minimiser;
+
+static const double stop_epsilon= 1e-6;
+
+static double minfunc_f(const gsl_vector *x, void *params) {
+ struct Vertices vs;
+
+ assert(x->size == DIM);
+ assert(x->stride == 1);
+ map_dimensions(x->data, vs.a);
+ return compute_energy(&vs);
+}
+
+int main(int argc, const char *const *argv) {
+ gsl_multimin_function multimin_function;
+ double size;
+ struct Vertices initial_full;
+ double initial_half[DIM], step_size[DIM];
+ FILE *initial_f;
+ gsl_vector initial_gsl, step_size_gsl;
+ int r, i;
+
+ 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");
+
+ graph_layout_prepare();
+ printing_init();
+
+ printf("X=%d=0x%x Y=%d=0x%x DIM=%d\n",X,X,Y,Y,DIM);
+
+ minimiser= gsl_multimin_fminimizer_alloc
+ (gsl_multimin_fminimizer_nmsimplex, DIM);
+ if (!minimiser) { perror("alloc minimiser"); exit(-1); }
+
+ multimin_function.f= minfunc_f;
+ multimin_function.n= DIM;
+ multimin_function.params= 0;
+
+ initial_f= fopen(input_file,"rb"); if (!initial_f) diee("fopen initial");
+ errno= 0; r= fread(&initial_full,sizeof(initial_full),1,initial_f);
+ if (r!=1) diee("fread");
+ fclose(initial_f);
+
+ pmap_dimensions(&initial_full);
+ unmap_dimensions(initial_half,&initial_full);
+ for (i=0; i<DIM; i++) step_size[i]= 0.03;
+
+ initial_gsl.size= DIM;
+ initial_gsl.stride= 1;
+ initial_gsl.block= 0;
+ initial_gsl.owner= 0;
+ step_size_gsl= initial_gsl;
+
+ initial_gsl.data= initial_half;
+ step_size_gsl.data= step_size;
+
+ GA( gsl_multimin_fminimizer_set(minimiser, &multimin_function,
+ &initial_gsl, &step_size_gsl) );
+
+ for (;;) {
+ GA( gsl_multimin_fminimizer_iterate(minimiser) );
+
+ size= gsl_multimin_fminimizer_size(minimiser);
+ r= gsl_multimin_test_size(size, stop_epsilon);
+
+ if (printing_check(pr_size))
+ printf("%*s size %# e, r=%d\n", 135,"", size, r);
+ flushoutput();
+
+ if (r==GSL_SUCCESS) break;
+ assert(r==GSL_CONTINUE);
+ }
+ return 0;
+}
+
+/*---------- printing rate limit ----------*/
+
+static volatile unsigned print_todo;
+static sigset_t print_alarmset;
+
+int printing_check(enum printing_instance which) {
+ static int skipped[pr__max];
+
+ unsigned bits= 1u << which;
+ int sk;
+
+ if (!(print_todo & bits)) {
+ skipped[which]++;
+ return 0;;
+ }
+
+ sigprocmask(SIG_BLOCK,&print_alarmset,0);
+ print_todo &= ~bits;
+ sigprocmask(SIG_UNBLOCK,&print_alarmset,0);
+
+ sk= skipped[which];
+ if (sk) printf("[%4d] ",sk);
+ else printf(" ");
+ skipped[which]= 0;
+
+ return 1;
+}
+
+static void alarmhandler(int ignored) {
+ print_todo= ~0u;
+}
+
+static void printing_init(void) {
+ struct sigaction sa;
+ struct itimerval itv;
+
+ sigemptyset(&print_alarmset);
+ sigaddset(&print_alarmset,SIGALRM);
+
+ sa.sa_handler= alarmhandler;
+ sa.sa_mask= print_alarmset;
+ sa.sa_flags= SA_RESTART;
+ if (sigaction(SIGALRM,&sa,0)) diee("sigaction ALRM");
+
+ itv.it_interval.tv_sec= 0;
+ itv.it_interval.tv_usec= 200000;
+ itv.it_value= itv.it_interval;
+
+ if (setitimer(ITIMER_REAL,&itv,0)) diee("setitimer REAL");
+
+ raise(SIGALRM);
+}