nlopt.c

#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <float.h>

#include "nlopt.h"
#include "nlopt-util.h"
#include "config.h"

#define MIN(a,b) ((a) < (b) ? (a) : (b))

/*************************************************************************/

#ifdef INFINITY
#  define MY_INF INFINITY
#else
#  define MY_INF HUGE_VAL
#endif

static int my_isinf(double x) {
     return fabs(x) >= HUGE_VAL * 0.99
#ifdef HAVE_ISINF
	  || isinf(x)
#endif
	  ;
}

#ifndef HAVE_ISNAN
static int my_isnan(double x) { return x != x; }
#  define isnan my_isnan
#endif

/*************************************************************************/

void nlopt_version(int *major, int *minor, int *bugfix)
{
     *major = MAJOR_VERSION;
     *minor = MINOR_VERSION;
     *bugfix = BUGFIX_VERSION;
}

/*************************************************************************/

static const char nlopt_algorithm_names[NLOPT_NUM_ALGORITHMS][128] = {
     "DIRECT (global, no-derivative)",
     "DIRECT-L (global, no-derivative)",
     "Randomized DIRECT-L (global, no-derivative)",
     "Unscaled DIRECT (global, no-derivative)",
     "Unscaled DIRECT-L (global, no-derivative)",
     "Unscaled Randomized DIRECT-L (global, no-derivative)",
     "Original DIRECT version (global, no-derivative)",
     "Original DIRECT-L version (global, no-derivative)",
     "Subplex (local, no-derivative)",
     "StoGO (global, derivative-based)",
     "StoGO with randomized search (global, derivative-based)",
     "Low-storage BFGS (LBFGS) (local, derivative-based)",
     "Principal-axis, praxis (local, no-derivative)",
     "Limited-memory variable-metric, rank 1 (local, derivative-based)",
     "Limited-memory variable-metric, rank 2 (local, derivative-based)",
};

const char *nlopt_algorithm_name(nlopt_algorithm a)
{
     if (a < 0 || a >= NLOPT_NUM_ALGORITHMS) return "UNKNOWN";
     return nlopt_algorithm_names[a];
}

/*************************************************************************/

static int nlopt_srand_called = 0;
void nlopt_srand(unsigned long seed) {
     nlopt_srand_called = 1;
     nlopt_init_genrand(seed);
}

void nlopt_srand_time() {
     nlopt_srand(nlopt_time_seed());
}

/*************************************************************************/

typedef struct {
     nlopt_func f;
     void *f_data;
     const double *lb, *ub;
} nlopt_data;

#include "subplex.h"
#include "praxis.h"

static double f_subplex(int n, const double *x, void *data_)
{
     int i;
     nlopt_data *data = (nlopt_data *) data_;
     double f;

     /* subplex does not support bound constraints, but it supports
	discontinuous objectives so we can just return Inf for invalid x */
     for (i = 0; i < n; ++i)
	  if (x[i] < data->lb[i] || x[i] > data->ub[i])
	       return MY_INF;

     f = data->f(n, x, NULL, data->f_data);
     return (isnan(f) ? MY_INF : f);
}

#include "direct.h"

static double f_direct(int n, const double *x, int *undefined, void *data_)
{
     nlopt_data *data = (nlopt_data *) data_;
     double f;
     f = data->f(n, x, NULL, data->f_data);
     *undefined = isnan(f) || my_isinf(f);
     return f;
}

#include "stogo.h"

#include "cdirect.h"

#include "luksan.h"

/*************************************************************************/

/* for "hybrid" algorithms that combine global search with some
   local search algorithm, most of the time we anticipate that people
   will stick with the default local search algorithm, so we
   don't add this as a parameter to nlopt_minimize.  Instead, the user
   can call nlopt_{set/get}_hybrid_local_algorithm to get/set the defaults. */

/* default local-search algorithms */
static nlopt_algorithm local_search_alg_deriv = NLOPT_LD_LBFGS;
static nlopt_algorithm local_search_alg_nonderiv = NLOPT_LN_SUBPLEX;

static int local_search_maxeval = -1; /* no maximum by default */

void nlopt_get_local_search_algorithm(nlopt_algorithm *deriv,
				      nlopt_algorithm *nonderiv,
				      int *maxeval)
{
     *deriv = local_search_alg_deriv;
     *nonderiv = local_search_alg_nonderiv;
     *maxeval = local_search_maxeval;
}

void nlopt_set_local_search_algorithm(nlopt_algorithm deriv,
				      nlopt_algorithm nonderiv,
				      int maxeval)
{
     local_search_alg_deriv = deriv;
     local_search_alg_nonderiv = nonderiv;
     local_search_maxeval = maxeval;
}

/*************************************************************************/

/* same as nlopt_minimize, but xtol_abs is required to be non-NULL */
static nlopt_result nlopt_minimize_(
     nlopt_algorithm algorithm,
     int n, nlopt_func f, void *f_data,
     const double *lb, const double *ub, /* bounds */
     double *x, /* in: initial guess, out: minimizer */
     double *minf, /* out: minimum */
     double minf_max, double ftol_rel, double ftol_abs,
     double xtol_rel, const double *xtol_abs,
     int maxeval, double maxtime)
{
     int i;
     nlopt_data d;
     nlopt_stopping stop;

     /* some basic argument checks */
     if (n <= 0 || !f || !lb || !ub || !x || !minf)
	  return NLOPT_INVALID_ARGS;

     d.f = f;
     d.f_data = f_data;
     d.lb = lb;
     d.ub = ub;

     /* make sure rand generator is inited */
     if (!nlopt_srand_called)
	  nlopt_srand_time(); /* default is non-deterministic */

     /* check bound constraints */
     for (i = 0; i < n; ++i)
	  if (lb[i] > ub[i] || x[i] < lb[i] || x[i] > ub[i])
	       return NLOPT_INVALID_ARGS;

     stop.n = n;
     stop.minf_max = (isnan(minf_max) || (my_isinf(minf_max) && minf_max < 0))
	  ? -MY_INF : minf_max;
     stop.ftol_rel = ftol_rel;
     stop.ftol_abs = ftol_abs;
     stop.xtol_rel = xtol_rel;
     stop.xtol_abs = xtol_abs;
     stop.nevals = 0;
     stop.maxeval = maxeval;
     stop.maxtime = maxtime;
     stop.start = nlopt_seconds();

     switch (algorithm) {
	 case NLOPT_GN_DIRECT:
	 case NLOPT_GN_DIRECT_L: 
	 case NLOPT_GN_DIRECT_L_RAND: 
	      return cdirect(n, f, f_data, lb, ub, x, minf, &stop, 0.0, 
			     (algorithm != NLOPT_GN_DIRECT)
			     + 3 * (algorithm == NLOPT_GN_DIRECT_L_RAND ? 2 : (algorithm != NLOPT_GN_DIRECT))
			     + 9 * (algorithm == NLOPT_GN_DIRECT_L_RAND ? 1 : (algorithm != NLOPT_GN_DIRECT)));
	      
	 case NLOPT_GN_DIRECT_NOSCAL:
	 case NLOPT_GN_DIRECT_L_NOSCAL: 
	 case NLOPT_GN_DIRECT_L_RAND_NOSCAL: 
	      return cdirect_unscaled(n, f, f_data, lb, ub, x, minf, 
				      &stop, 0.0, 
				      (algorithm != NLOPT_GN_DIRECT)
				      + 3 * (algorithm == NLOPT_GN_DIRECT_L_RAND ? 2 : (algorithm != NLOPT_GN_DIRECT))
				      + 9 * (algorithm == NLOPT_GN_DIRECT_L_RAND ? 1 : (algorithm != NLOPT_GN_DIRECT)));
	      
	 case NLOPT_GN_ORIG_DIRECT:
	 case NLOPT_GN_ORIG_DIRECT_L: 
	      switch (direct_optimize(f_direct, &d, n, lb, ub, x, minf,
				      maxeval, -1, 0.0, 0.0,
				      pow(xtol_rel, (double) n), -1.0,
				      stop.minf_max, 0.0,
				      NULL, 
				      algorithm == NLOPT_GN_ORIG_DIRECT
				      ? DIRECT_ORIGINAL
				      : DIRECT_GABLONSKY)) {
		  case DIRECT_INVALID_BOUNDS:
		  case DIRECT_MAXFEVAL_TOOBIG:
		  case DIRECT_INVALID_ARGS:
		       return NLOPT_INVALID_ARGS;
		  case DIRECT_INIT_FAILED:
		  case DIRECT_SAMPLEPOINTS_FAILED:
		  case DIRECT_SAMPLE_FAILED:
		       return NLOPT_FAILURE;
		  case DIRECT_MAXFEVAL_EXCEEDED:
		  case DIRECT_MAXITER_EXCEEDED:
		       return NLOPT_MAXEVAL_REACHED;
		  case DIRECT_GLOBAL_FOUND:
		       return NLOPT_MINF_MAX_REACHED;
		  case DIRECT_VOLTOL:
		  case DIRECT_SIGMATOL:
		       return NLOPT_XTOL_REACHED;
		  case DIRECT_OUT_OF_MEMORY:
		       return NLOPT_OUT_OF_MEMORY;
	      break;
	 }

	 case NLOPT_GD_STOGO:
	 case NLOPT_GD_STOGO_RAND:
	      if (!stogo_minimize(n, f, f_data, x, minf, lb, ub, &stop,
				  algorithm == NLOPT_GD_STOGO
				  ? 0 : 2*n))
		   return NLOPT_FAILURE;
	      break;

	 case NLOPT_LN_SUBPLEX: {
	      int iret;
	      double *scale = (double *) malloc(sizeof(double) * n);
	      if (!scale) return NLOPT_OUT_OF_MEMORY;
	      for (i = 0; i < n; ++i) {
		   if (!my_isinf(ub[i]) && !my_isinf(lb[i]))
			scale[i] = (ub[i] - lb[i]) * 0.01;
		   else if (!my_isinf(lb[i]) && x[i] > lb[i])
			scale[i] = (x[i] - lb[i]) * 0.01;
		   else if (!my_isinf(ub[i]) && x[i] < ub[i])
			scale[i] = (ub[i] - x[i]) * 0.01;
		   else
			scale[i] = 0.01 * x[i] + 0.0001;
	      }
	      iret = subplex(f_subplex, minf, x, n, &d, &stop, scale);
	      free(scale);
	      switch (iret) {
		  case -2: return NLOPT_INVALID_ARGS;
		  case -10: return NLOPT_MAXTIME_REACHED;
		  case -1: return NLOPT_MAXEVAL_REACHED;
		  case 0: return NLOPT_XTOL_REACHED;
		  case 1: return NLOPT_SUCCESS;
		  case 2: return NLOPT_MINF_MAX_REACHED;
		  case 20: return NLOPT_FTOL_REACHED;
		  case -200: return NLOPT_OUT_OF_MEMORY;
		  default: return NLOPT_FAILURE; /* unknown return code */
	      }
	      break;
	 }

	 case NLOPT_LN_PRAXIS: {
	      double h0 = HUGE_VAL;
	      for (i = 0; i < n; ++i) {
		   if (!my_isinf(ub[i]) && !my_isinf(lb[i]))
			h0 = MIN(h0, (ub[i] - lb[i]) * 0.01);
		   else if (!my_isinf(lb[i]) && x[i] > lb[i])
			h0 = MIN(h0, (x[i] - lb[i]) * 0.01);
		   else if (!my_isinf(ub[i]) && x[i] < ub[i])
			h0 = MIN(h0, (ub[i] - x[i]) * 0.01);
		   else
			h0 = MIN(h0, 0.01 * x[i] + 0.0001);
	      }
	      return praxis_(0.0, DBL_EPSILON, h0, n, x, f_subplex, &d,
			     &stop, minf);
	 }

	 case NLOPT_LD_LBFGS: 
	      return luksan_plis(n, f, f_data, lb, ub, x, minf, &stop);

	 case NLOPT_LD_VAR1: 
	 case NLOPT_LD_VAR2: 
	      return luksan_plip(n, f, f_data, lb, ub, x, minf, &stop,
		   algorithm == NLOPT_LD_VAR1 ? 1 : 2);

	 default:
	      return NLOPT_INVALID_ARGS;
     }

     return NLOPT_SUCCESS;
}

nlopt_result nlopt_minimize(
     nlopt_algorithm algorithm,
     int n, nlopt_func f, void *f_data,
     const double *lb, const double *ub, /* bounds */
     double *x, /* in: initial guess, out: minimizer */
     double *minf, /* out: minimum */
     double minf_max, double ftol_rel, double ftol_abs,
     double xtol_rel, const double *xtol_abs,
     int maxeval, double maxtime)
{
     nlopt_result ret;
     if (xtol_abs)
	  ret = nlopt_minimize_(algorithm, n, f, f_data, lb, ub,
				x, minf, minf_max, ftol_rel, ftol_abs,
				xtol_rel, xtol_abs, maxeval, maxtime);
     else {
	  int i;
	  double *xtol = (double *) malloc(sizeof(double) * n);
	  if (!xtol) return NLOPT_OUT_OF_MEMORY;
	  for (i = 0; i < n; ++i) xtol[i] = -1;
	  ret = nlopt_minimize_(algorithm, n, f, f_data, lb, ub,
				x, minf, minf_max, ftol_rel, ftol_abs,
				xtol_rel, xtol, maxeval, maxtime);
	  free(xtol);
     }
     return ret;
}