Fixed fft_inplace() not compiling for compile time sized matrices.

dlib/matrix/matrix_fft.h

@@ -472,7 +472,7 @@ namespace dlib
 // ----------------------------------------------------------------------------------------
 
     template < typename T, long NR, long NC, typename MM, typename L >
-    void fft_inplace (matrix<std::complex<T>,NR,NC,MM,L>& data)
+    typename enable_if_c<NR==1||NC==1>::type fft_inplace (matrix<std::complex<T>,NR,NC,MM,L>& data)
     // Note that we don't divide the outputs by data.size() so this isn't quite the inverse.
     {
         // make sure requires clause is not broken
@@ -485,19 +485,31 @@ namespace dlib
             << "\n\t is_power_of_two(data.nc()): " << is_power_of_two(data.nc())
             );
 
-        if (data.nr() == 1 || data.nc() == 1)
-        {
         impl::twiddles<T> cs;
         impl::fft1d_inplace(data, false, cs);
     }
-        else
+
+    template < typename T, long NR, long NC, typename MM, typename L >
+    typename disable_if_c<NR==1||NC==1>::type fft_inplace (matrix<std::complex<T>,NR,NC,MM,L>& data)
+    // Note that we don't divide the outputs by data.size() so this isn't quite the inverse.
     {
+        // make sure requires clause is not broken
+        DLIB_CASSERT(is_power_of_two(data.nr()) && is_power_of_two(data.nc()),
+            "\t void fft_inplace(data)"
+            << "\n\t The number of rows and columns must be powers of two."
+            << "\n\t data.nr(): "<< data.nr()
+            << "\n\t data.nc(): "<< data.nc()
+            << "\n\t is_power_of_two(data.nr()): " << is_power_of_two(data.nr())
+            << "\n\t is_power_of_two(data.nc()): " << is_power_of_two(data.nc())
+            );
+
         impl::fft2d_inplace(data, false);
     }
-    }
+
+// ----------------------------------------------------------------------------------------
 
     template < typename T, long NR, long NC, typename MM, typename L >
-    void ifft_inplace (matrix<std::complex<T>,NR,NC,MM,L>& data)
+    typename enable_if_c<NR==1||NC==1>::type ifft_inplace (matrix<std::complex<T>,NR,NC,MM,L>& data)
     {
         // make sure requires clause is not broken
         DLIB_CASSERT(is_power_of_two(data.nr()) && is_power_of_two(data.nc()),
@@ -509,16 +521,25 @@ namespace dlib
             << "\n\t is_power_of_two(data.nc()): " << is_power_of_two(data.nc())
             );
 
-        if (data.nr() == 1 || data.nc() == 1)
-        {
         impl::twiddles<T> cs;
         impl::fft1d_inplace(data, true, cs);
     }
-        else
+
+    template < typename T, long NR, long NC, typename MM, typename L >
+    typename disable_if_c<NR==1||NC==1>::type ifft_inplace (matrix<std::complex<T>,NR,NC,MM,L>& data)
     {
+        // make sure requires clause is not broken
+        DLIB_CASSERT(is_power_of_two(data.nr()) && is_power_of_two(data.nc()),
+            "\t void ifft_inplace(data)"
+            << "\n\t The number of rows and columns must be powers of two."
+            << "\n\t data.nr(): "<< data.nr()
+            << "\n\t data.nc(): "<< data.nc()
+            << "\n\t is_power_of_two(data.nr()): " << is_power_of_two(data.nr())
+            << "\n\t is_power_of_two(data.nc()): " << is_power_of_two(data.nc())
+            );
+
         impl::fft2d_inplace(data, true);
     }
-    }
 
 // ----------------------------------------------------------------------------------------
 

dlib/test/fft.cpp

@@ -98,6 +98,28 @@ namespace
 
 // ----------------------------------------------------------------------------------------
 
+    template <long nr, long nc>
+    void test_real_compile_time_sized_ffts()
+    {
+        print_spinner();
+        const matrix<complex<double>,nr,nc> m1 = complex_matrix(real(rand_complex(nr,nc)));
+        const matrix<complex<float>,nr,nc> fm1 = matrix_cast<complex<float> >(complex_matrix(real(rand_complex(nr,nc))));
+
+        DLIB_TEST(max(norm(ifft(fft(complex_matrix(real(m1))))-m1)) < 1e-16);
+        DLIB_TEST(max(norm(ifft(fft(complex_matrix(real(fm1))))-fm1)) < 1e-7);
+
+        matrix<complex<double>,nr,nc> temp = m1;
+        matrix<complex<float>,nr,nc> ftemp = fm1;
+        fft_inplace(temp);
+        fft_inplace(ftemp);
+        DLIB_TEST(max(norm(temp-fft(m1))) < 1e-16);
+        DLIB_TEST(max(norm(ftemp-fft(fm1))) < 1e-7);
+        ifft_inplace(temp);
+        ifft_inplace(ftemp);
+        DLIB_TEST(max(norm(temp/temp.size()-m1)) < 1e-16);
+        DLIB_TEST(max(norm(ftemp/ftemp.size()-fm1)) < 1e-7);
+    }
+
     void test_random_real_ffts()
     {
         for (int iter = 0; iter < 10; ++iter)
@@ -126,6 +148,10 @@ namespace
                 }
             }
         }
+
+        test_real_compile_time_sized_ffts<16,16>();
+        test_real_compile_time_sized_ffts<16,1>();
+        test_real_compile_time_sized_ffts<1,16>();
     }
 
 // ----------------------------------------------------------------------------------------