/// <summary>
/// 時間領域データから作成。
/// </summary>
/// <param name="x">時間領域データ</param>
/// <param name="length">データの長さ</param>
/// <param name="skip">読み飛ばす長さ</param>
/// <returns>作成された周波数特性</returns>
public static Spectrum FromTimeSequence(double[] x, int length, int skip)
{
if (x == null)
{
return(null);
}
int len = BitOperation.FloorPower2(length);
double[] tmp = new double[len];
for (int i = 0; i < len; ++i)
{
tmp[i] = x[skip + i];
}
Fft fft = new Fft(len);
fft.Transform(tmp);
return(new Spectrum(tmp));
}