minor code cleanup

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402344

dlib/matrix/matrix.h

@@ -1347,7 +1347,7 @@ namespace dlib
     )
     {
         typedef matrix_mulscal_exp<matrix_exp<EXP>,float >  exp;
-        return matrix_exp<exp>(exp(m,1/s));
+        return matrix_exp<exp>(exp(m,1.0f/s));
     }
 
     template <