AForge.Math.FourierTransform.FFT2 C# (CSharp) Method

        public static void FFT2(Complex[,] data, Direction direction)
        {
            int k = data.GetLength(0);
            int n = data.GetLength(1);

            // check data size
            if (
                (!Tools.IsPowerOf2(k)) ||
                (!Tools.IsPowerOf2(n)) ||
                (k < minLength) || (k > maxLength) ||
                (n < minLength) || (n > maxLength)
                )
            {
                throw new ArgumentException("Incorrect data length.");
            }

            // process rows
            var row = new Complex[n];

            for (int i = 0; i < k; i++)
            {
                // copy row
                for (int j = 0; j < n; j++)
                    row[j] = data[i, j];
                // transform it
                FFT(row, direction);
                // copy back
                for (int j = 0; j < n; j++)
                    data[i, j] = row[j];
            }

            // process columns
            var col = new Complex[k];

            for (int j = 0; j < n; j++)
            {
                // copy column
                for (int i = 0; i < k; i++)
                    col[i] = data[i, j];
                // transform it
                FFT(col, direction);
                // copy back
                for (int i = 0; i < k; i++)
                    data[i, j] = col[i];
            }
        }