- Added a compile time check for function references

  - Made the optimization routines return the value of the objective
    function at the end of optimization.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403219

dlib/optimization/optimization.h

@@ -130,7 +130,7 @@ namespace dlib
         typename funct_der, 
         typename T
         >
-    void find_min (
+    double find_min (
         search_strategy_type search_strategy,
         stop_strategy_type stop_strategy,
         const funct& f, 
@@ -175,6 +175,8 @@ namespace dlib
             // Take the search step indicated by the above line search
             x += alpha*s;
         }
+
+        return f_value;
     }
 
 // ----------------------------------------------------------------------------------------
@@ -186,7 +188,7 @@ namespace dlib
         typename funct_der, 
         typename T
         >
-    void find_max (
+    double find_max (
         search_strategy_type search_strategy,
         stop_strategy_type stop_strategy,
         const funct& f, 
@@ -239,6 +241,7 @@ namespace dlib
             f_value *= -1;
         }
 
+        return -f_value;
     }
 
 // ----------------------------------------------------------------------------------------
@@ -249,7 +252,7 @@ namespace dlib
         typename funct,
         typename T
         >
-    void find_min_using_approximate_derivatives (
+    double find_min_using_approximate_derivatives (
         search_strategy_type search_strategy,
         stop_strategy_type stop_strategy,
         const funct& f,
@@ -297,6 +300,7 @@ namespace dlib
             g = derivative(f,derivative_eps)(x);
         }
 
+        return f_value;
     }
 
 // ----------------------------------------------------------------------------------------
@@ -307,7 +311,7 @@ namespace dlib
         typename funct,
         typename T
         >
-    void find_max_using_approximate_derivatives (
+    double find_max_using_approximate_derivatives (
         search_strategy_type search_strategy,
         stop_strategy_type stop_strategy,
         const funct& f,
@@ -333,7 +337,7 @@ namespace dlib
         );
 
         // Just negate the necessary things and call the find_min version of this function.
-        find_min_using_approximate_derivatives(
+        return -find_min_using_approximate_derivatives(
             search_strategy, 
             stop_strategy, 
             negate_function(f),

dlib/optimization/optimization_abstract.h

@@ -102,7 +102,7 @@ namespace dlib
         typename funct_der, 
         typename T
         >
-    void find_min (
+    double find_min (
         search_strategy_type search_strategy,
         stop_strategy_type stop_strategy,
         const funct& f, 
@@ -125,6 +125,7 @@ namespace dlib
             - The function is optimized until stop_strategy decides that an acceptable 
               point has been found or f(#x) < min_f.
             - #x == the value of x that was found to minimize f()
+            - returns f(#x). 
             - When this function makes calls to f() and der() it always does so by
               first calling f() and then calling der().  That is, these two functions
               are always called in pairs with f() being called first and then der()
@@ -140,7 +141,7 @@ namespace dlib
         typename funct_der, 
         typename T
         >
-    void find_max (
+    double find_max (
         search_strategy_type search_strategy,
         stop_strategy_type stop_strategy,
         const funct& f, 
@@ -163,6 +164,7 @@ namespace dlib
             - The function is optimized until stop_strategy decides that an acceptable 
               point has been found or f(#x) > max_f.
             - #x == the value of x that was found to maximize f()
+            - returns f(#x). 
             - When this function makes calls to f() and der() it always does so by
               first calling f() and then calling der().  That is, these two functions
               are always called in pairs with f() being called first and then der()
@@ -177,7 +179,7 @@ namespace dlib
         typename funct,
         typename T
         >
-    void find_min_using_approximate_derivatives (
+    double find_min_using_approximate_derivatives (
         search_strategy_type search_strategy,
         stop_strategy_type stop_strategy,
         const funct& f,
@@ -200,6 +202,7 @@ namespace dlib
             - The function is optimized until stop_strategy decides that an acceptable 
               point has been found or f(#x) < min_f.
             - #x == the value of x that was found to minimize f()
+            - returns f(#x). 
             - Uses the dlib::derivative(f,derivative_eps) function to compute gradient
               information.
     !*/
@@ -212,7 +215,7 @@ namespace dlib
         typename funct,
         typename T
         >
-    void find_max_using_approximate_derivatives (
+    double find_max_using_approximate_derivatives (
         search_strategy_type search_strategy,
         stop_strategy_type stop_strategy,
         const funct& f,
@@ -235,6 +238,7 @@ namespace dlib
             - The function is optimized until stop_strategy decides that an acceptable 
               point has been found or f(#x) > max_f.
             - #x == the value of x that was found to maximize f()
+            - returns f(#x). 
             - Uses the dlib::derivative(f,derivative_eps) function to compute gradient
               information.
     !*/

dlib/optimization/optimization_bobyqa.h

@@ -46,7 +46,7 @@ namespace dlib
             typename T, 
             typename U
             >
-        void find_min (
+        double find_min (
             const funct& f,
             T& x,
             long npt,
@@ -68,7 +68,7 @@ namespace dlib
             matrix<double,0,1> xu(xu_);
 
             
-            bobyqa_ (f,
+            return bobyqa_ (f,
                             x.size(),
                             npt,
                             &x(0),
@@ -84,7 +84,7 @@ namespace dlib
 
 
         template <typename funct>
-        void bobyqa_(
+        doublereal bobyqa_(
             const funct& calfun,
             const integer n, 
             const integer npt, 
@@ -225,7 +225,7 @@ namespace dlib
 
             /*     Make the call of BOBYQB. */
 
-            bobyqb_(calfun, n, npt, &x[1], &xl[1], &xu[1], rhobeg, rhoend, maxfun, &w[
+            return bobyqb_(calfun, n, npt, &x[1], &xl[1], &xu[1], rhobeg, rhoend, maxfun, &w[
                     ixb], &w[ixp], &w[ifv], &w[ixo], &w[igo], &w[ihq], &w[ipq], &w[
                     ibmat], &w[izmat], ndim, &w[isl], &w[isu], &w[ixn], &w[ixa], &w[
                     id], &w[ivl], &w[iw]);
@@ -236,7 +236,7 @@ namespace dlib
     // ----------------------------------------------------------------------------------------
 
         template <typename funct>
-        void bobyqb_(
+        doublereal bobyqb_(
             const funct& calfun,
             const integer n,
             const integer npt,
@@ -271,7 +271,7 @@ namespace dlib
             doublereal d__1, d__2, d__3, d__4;
 
             /* Local variables */
-            doublereal f;
+            doublereal f = 0;
             integer i__, j, k, ih, nf, jj, nh, ip, jp;
             doublereal dx;
             integer np;
@@ -1320,6 +1320,7 @@ L720:
                 f = fval[kopt];
             }
 
+            return f;
         } /* bobyqb_ */
 
     // ----------------------------------------------------------------------------------------
@@ -3344,7 +3345,7 @@ L210:
         typename T, 
         typename U
         >
-    void find_min_bobyqa (
+    double find_min_bobyqa (
         const funct& f,
         T& x,
         long npt,
@@ -3355,6 +3356,14 @@ L210:
         const long max_f_evals
     ) 
     {
+        // You get an error on this line when you pass in a global function to this function.
+        // You have to either use a function object or pass a pointer to your global function
+        // by taking its address using the & operator.  (This check is here because gcc 4.0
+        // has a bug that causes it to silently corrupt return values from functions that
+        // invoked through a reference)
+        COMPILE_TIME_ASSERT(is_function<funct>::value == false);
+
+
         // check the requirements.  Also split the assert up so that the error message isn't huge.
         DLIB_CASSERT(is_col_vector(x) && is_col_vector(x_lower) && is_col_vector(x_upper) &&
                     x.size() == x_lower.size() && x_lower.size() == x_upper.size() &&
@@ -3386,7 +3395,7 @@ L210:
 
 
         bobyqa_implementation impl;
-        impl.find_min(f, x, npt, x_lower, x_upper, rho_begin, rho_end, max_f_evals);
+        return impl.find_min(f, x, npt, x_lower, x_upper, rho_begin, rho_end, max_f_evals);
     }
 
 // ----------------------------------------------------------------------------------------
@@ -3396,7 +3405,7 @@ L210:
         typename T, 
         typename U
         >
-    void find_max_bobyqa (
+    double find_max_bobyqa (
         const funct& f,
         T& x,
         long npt,
@@ -3407,7 +3416,7 @@ L210:
         const long max_f_evals
     ) 
     {
-        find_min_bobyqa(negate_function(f), x, npt, x_lower, x_upper, rho_begin, rho_end, max_f_evals);
+        return -find_min_bobyqa(negate_function(f), x, npt, x_lower, x_upper, rho_begin, rho_end, max_f_evals);
     }
 
 // ----------------------------------------------------------------------------------------

dlib/optimization/optimization_bobyqa_abstract.h

@@ -41,7 +41,7 @@ namespace dlib
         typename T, 
         typename U
         >
-    void find_min_bobyqa (
+    double find_min_bobyqa (
         const funct& f,
         T& x,
         long npt,
@@ -75,6 +75,7 @@ namespace dlib
             - #x == the value of x (within the bounds defined by x_lower and x_upper) that 
               was found to minimize f().  More precisely:
                 - min(#x - x_lower) >= 0 && min(x_upper - #x) >= 0
+            - returns f(#x). 
             - rho_begin and rho_end are used as the initial and final values of a trust 
               region radius.  Typically, rho_begin should be about one tenth of the greatest 
               expected change to a variable, while rho_end should indicate the accuracy that 
@@ -94,7 +95,7 @@ namespace dlib
         typename T, 
         typename U
         >
-    void find_max_bobyqa (
+    double find_max_bobyqa (
         const funct& f,
         T& x,
         long npt,