Added a function to the gate_exp() to return a matrix object for the gate.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402693

dlib/quantum_computing/quantum_computing.h

@@ -272,6 +272,19 @@ namespace dlib
 
         const qc_scalar_type operator() (long r, long c) const { return exp(r,c); }
 
+        const matrix<qc_scalar_type> mat (
+        ) const
+        {
+            matrix<qc_scalar_type,dims,dims> m;
+            for (long r = 0; r < m.nr(); ++r)
+            {
+                for (long c = 0; c < m.nc(); ++c)
+                {
+                    m(r,c) = exp(r,c);
+                }
+            }
+            return m;
+        }
 
         void apply_gate_to (quantum_register& reg) const
         {

dlib/quantum_computing/quantum_computing_abstract.h

@@ -255,6 +255,12 @@ namespace dlib
                 - returns a reference to the subexpression contained in this object
         !*/
 
+        const matrix<qc_scalar_type> mat (
+        ) const;
+        /*!
+            ensures
+                - returns a dense matrix object that contains the matrix for this gate
+        !*/
     };
 
 // ----------------------------------------------------------------------------------------