Accord.Math.PerlinNoise.Function C# (CSharp) Method

        public double Function(double x)
        {
            double frequency = initFrequency;
            double amplitude = initAmplitude;
            double sum = 0;

            // octaves
            for (int i = 0; i < octaves; i++)
            {
                sum += SmoothedNoise(x * frequency) * amplitude;

                frequency *= 2;
                amplitude *= persistence;
            }
            return sum;
        }