/// <summary>
        /// Verify matches naive complex.
        /// </summary>
        static void VerifyMatchesNaiveComplex(
            Complex[] samples,
            int maximumErrorDecimalPlaces,
            Func<Complex[], Complex[]> naive,
            Action<Complex[]> fast)
        {
            var spectrumNaive = naive(samples);

            var spectrumFast = new Complex[samples.Length];
            samples.CopyTo(spectrumFast, 0);
            fast(spectrumFast);

            AssertHelpers.ListAlmostEqual(spectrumNaive, spectrumFast, maximumErrorDecimalPlaces);
        }