text: /* C-style API for DIRECT functions.  SGJ (August 2007). */
  
  #include "direct-internal.h"
  
  /* Perform global minimization using (Gablonsky implementation of) DIRECT
     algorithm.   Arguments:
  
     f, f_data: the objective function and any user data
     -- the objective function f(n, x, undefined_flag, data) takes 4 args:
     int n: the dimension, same as dimension arg. to direct_optimize
     const double *x: array x[n] of point to evaluate
     int *undefined_flag: set to 1 on return if x violates constraints
     or don't touch otherwise
     void *data: same as f_data passed to direct_optimize
     return value = value of f(x)
  
     dimension: the number of minimization variable dimensions
     lower_bounds, upper_bounds: arrays of length dimension of variable bounds
  
     x: an array of length dimension, set to optimum variables upon return
     minf: on return, set to minimum f value
  
     magic_eps, magic_eps_abs: Jones' "magic" epsilon parameter, and
     also an absolute version of the same
     (not multipled by minf).  Jones suggests
     setting this to 1e-4, but 0 also works...
  
     max_feval, max_iter: maximum number of function evaluations & DIRECT iters
     volume_reltol: relative tolerance on hypercube volume (0 if none)
     sigma_reltol: relative tolerance on hypercube "measure" (??) (0 if none)
  
     fglobal: the global minimum of f, if known ahead of time
     -- this is mainly for benchmarking, in most cases it
     is not known and you should pass DIRECT_UNKNOWN_FGLOBAL
     fglobal_reltol: relative tolerance on how close we should find fglobal
     -- ignored if fglobal is DIRECT_UNKNOWN_FGLOBAL
  
     logfile: an output file to write diagnostic info to (NULL for no I/O)
  
     algorithm: whether to use the original DIRECT algorithm (DIRECT_ORIGINAL)
     or Gablonsky's "improved" version (DIRECT_GABLONSKY)
     */
  direct_return_code direct_optimize(
     direct_objective_func f, void *f_data,
     int dimension,
     const double *lower_bounds, const double *upper_bounds,
  
     double *x, double *minf,
  
     int max_feval, int max_iter,
     double start, double maxtime,
     double magic_eps, double magic_eps_abs,
     double volume_reltol, double sigma_reltol,
     int *force_stop,
  
     double fglobal,
     double fglobal_reltol,
  
     FILE *logfile,
     direct_algorithm algorithm)
  {
     integer algmethod = algorithm == DIRECT_GABLONSKY;
     integer ierror;
     doublereal *l, *u;
     int i;
  
     /* convert to percentages: */
     volume_reltol *= 100;
     sigma_reltol *= 100;
     fglobal_reltol *= 100;
  
     /* make sure these are ignored if <= 0 */
     if (volume_reltol <= 0) volume_reltol = -1;
     if (sigma_reltol <= 0) sigma_reltol = -1;
  
     if (fglobal == DIRECT_UNKNOWN_FGLOBAL)
        fglobal_reltol = DIRECT_UNKNOWN_FGLOBAL_RELTOL;
  
     if (dimension < 1) return DIRECT_INVALID_ARGS;
  
     l = (doublereal *)malloc(sizeof(doublereal) * dimension * 2);
     if (!l) return DIRECT_OUT_OF_MEMORY;
     u = l + dimension;
     for (i = 0; i < dimension; ++i) {
        l[i] = lower_bounds[i];
        u[i] = upper_bounds[i];
     }
  
     direct_direct_(f, x, &dimension, &magic_eps, magic_eps_abs,
                    &max_feval, &max_iter,
                    start, maxtime, force_stop,
                    minf,
                    l, u,
                    &algmethod,
                    &ierror,
                    logfile,
                    &fglobal, &fglobal_reltol,
                    &volume_reltol, &sigma_reltol,
                    f_data);
  
     free(l);
  
     return (direct_return_code)ierror;
  }
  