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compphys/exo2/testFFT.m
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testFFT.m
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% This script tests functor.m for correctness
functor = @(x) myfft(x);
fprintf('Test 1: Gaussian ...');
sample = exp(-linspace(-4,4,256).^2);
assert(all(abs(functor(sample) - fft(sample))<1e-10));
fprintf('\tpassed\n');
fprintf('Test 1.1: Gaussian with a different Matlab dimension ...');
sample = exp(-linspace(-4,4,256).^2)';
assert(all(abs(functor(sample) - fft(sample))<1e-10));
fprintf('\tpassed\n');
fprintf('Test 1.2: Gaussian complex ...');
sample = 1i*exp(-linspace(-4,4,256).^2);
assert(all(abs(functor(sample) - fft(sample))<1e-10));
fprintf('\tpassed\n');
fprintf('Test 2: sawtooth ...');
sample = linspace(-1,1,256);
assert(all(abs(functor(sample) - fft(sample))<1e-10));
fprintf('\tpassed\n');
fprintf('Test 3: sin and sin2 ...');
sample = sin(linspace(-pi,pi,256));
assert(all(abs(functor(sample) - fft(sample))<1e-10));
sample = sin(2*linspace(-pi,pi,256));
assert(all(abs(functor(sample) - fft(sample))<1e-10));
fprintf('\tpassed\n');
Ns = 10:25;
times = zeros(length(Ns),1);
FFTtimes = zeros(length(Ns),1);
% Time complexity test
for k=Ns
fprintf('\tEvaluating step %d \n', k);
sample = exp(-linspace(-4,4,2^k).^2)';
% functor time
tic;
functor(sample);
times(k-Ns(1)+1) = toc;
% fft time
tic;
fft(sample);
FFTtimes(k-Ns(1)+1) = toc;
end
Ns = 2.^Ns
% output to external file
fout = fopen("output/complexTimeFFT.out", 'w');
fprintf(fout, "N T FFT\n")
for k = 1:length(Ns)
fprintf(fout, "%g %g %g\n", Ns(k), times(k), FFTtimes(k))
end
fclose(fout);
% show graph
figure
grid on
xlabel('N')
ylabel('Elapsed time')
loglog(Ns, times, Ns, FFTtimes)
fprintf('All tests passed!\n');
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