Added a missing type cast to the reciprocal() function to fix a compile

time error you get when you use it with complex<float> type matrices.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403023

dlib/matrix/matrix_math_functions.h

@@ -266,7 +266,7 @@ DLIB_MATRIX_SIMPLE_STD_FUNCTION(atan,7)
             { 
                 const type temp = m(r,c);
                 if (temp != static_cast<type>(0))
-                    return static_cast<type>(1.0/temp);
+                    return static_cast<type>((type)1.0/temp);
                 else
                     return 0;
             }

dlib/test/matrix2.cpp

@@ -851,6 +851,23 @@ namespace
             DLIB_TEST(complex_matrix(a,b)(2,1) == std::complex<double>(0,0));
         }
 
+        {
+            matrix<complex<double> > m(2,2), m2(2,2);
+            complex<double> val1(1,2), val2(1.0/complex<double>(1,2));
+            m = val1;
+            m2 = val2;
+
+            DLIB_TEST(reciprocal(m) == m2);
+        }
+        {
+            matrix<complex<float> > m(2,2), m2(2,2);
+            complex<float> val1(1,2), val2(1.0f/complex<float>(1,2));
+            m = val1;
+            m2 = val2;
+
+            DLIB_TEST(reciprocal(m) == m2);
+        }
+
         {
             matrix<float,3,1> m1, m2;
             set_all_elements(m1,2.0);