Function test_linearity_real

dlib/test/fft.cpp:277–324

    
    template<typename R>
    void test_linearity_real()
    {
        static constexpr double tol = std::is_same<R,double>::value ? 1e-15 : 1e-3;
        static constexpr const char* typelabel = std::is_same<R,double>::value ? "double" : "float";
        
        int test = 0;
        
        auto func = [&](long nr, long nc)
        {
            if (++test % 100 == 0)
                print_spinner();

            const matrix<R> m1 = rand_real<R>(nr,nc);
            const matrix<R> m2 = rand_real<R>(nr,nc);
            const R a1 = rnd.get_double_in_range(-10.0, 10.0);
            const R a2 = rnd.get_double_in_range(-10.0, 10.0);
            const matrix<R> m3 = a1*m1 + a2*m2;

            const matrix<complex<R>> f1 = fftr(m1);
            const matrix<complex<R>> f2 = fftr(m2);
            const matrix<complex<R>> f3 = fftr(m3);

            DLIB_TEST(f1.nr() == m1.nr());
            DLIB_TEST(f1.nc() == fftr_nc_size(m1.nc()));

            R diff = max(norm(f3 - a1*f1 - a2*f2));
            DLIB_TEST_MSG(diff < tol, "diff " << diff << " not within tol " << tol << " where (nr,nc) = (" << nr << "," << nc << ")" << " type " << typelabel);

            const matrix<R> m4 = ifftr(f3);
            DLIB_TEST(m4.nr() == f3.nr());
            DLIB_TEST(m4.nc() == ifftr_nc_size(f3.nc()));

            diff = max(squared(m4 - m3));
            DLIB_TEST_MSG(diff < tol, "diff " << diff << " not within tol " << tol << " where (nr,nc) = (" << nr << "," << nc << ")" << " type " << typelabel);
        };
        
        for (int nr = 2; nr <= 64; nr += 2)
        {
            for (int nc = 2; nc <= 64; nc += 2)
            {
                func(nr,nc);
            }
        }
        
        //some odd balls...
        func(89, 102);  print_spinner();
        func(123, 48);   print_spinner();
    }

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