public static double num_flops(int N)
{
double num1 = (double)N;
double num2 = (double)FFT.log2(N);
return((5.0 * num1 - 2.0) * num2 + 2.0 * (num1 + 1.0));
}
protected internal static void transform_internal(double[] data, int direction)
{
if (data.Length == 0)
{
return;
}
int n = data.Length / 2;
if (n == 1)
{
return;
}
int num1 = FFT.log2(n);
FFT.bitreverse(data);
int num2 = 0;
int num3 = 1;
while (num2 < num1)
{
double num4 = 1.0;
double num5 = 0.0;
double a = 2.0 * (double)direction * Math.PI / (2.0 * (double)num3);
double num6 = Math.Sin(a);
double num7 = Math.Sin(a / 2.0);
double num8 = 2.0 * num7 * num7;
int num9 = 0;
while (num9 < n)
{
int index1 = checked (2 * num9);
int index2 = checked (2 * num9 + num3);
double num10 = data[index2];
double num11 = data[checked (index2 + 1)];
data[index2] = data[index1] - num10;
data[checked (index2 + 1)] = data[checked (index1 + 1)] - num11;
data[index1] += num10;
data[checked (index1 + 1)] += num11;
checked { num9 += 2 * num3; }
}
int num12 = 1;
while (num12 < num3)
{
double num10 = num4 - num6 * num5 - num8 * num4;
double num11 = num5 + num6 * num4 - num8 * num5;
num4 = num10;
num5 = num11;
int num13 = 0;
while (num13 < n)
{
int index1 = checked (2 * num13 + num12);
int index2 = checked (2 * num13 + num12 + num3);
double num14 = data[index2];
double num15 = data[checked (index2 + 1)];
double num16 = num4 * num14 - num5 * num15;
double num17 = num4 * num15 + num5 * num14;
data[index2] = data[index1] - num16;
data[checked (index2 + 1)] = data[checked (index1 + 1)] - num17;
data[index1] += num16;
data[checked (index1 + 1)] += num17;
checked { num13 += 2 * num3; }
}
checked { ++num12; }
}
checked { ++num2; }
checked { num3 *= 2; }
}
}
