numpy.sinc¶
-
numpy.
sinc
(x)[source]¶ 返回sinc函数。
sinc函数为。
参数: x:ndarray
要计算
sinc(x)
的值的数组(可能是多维的)。返回: out:ndarray
sinc(x)
,其具有与输入相同的形状。笔记
sinc(0)
是极限值1。名称sinc是“sine cardinal”或“sinus cardinalis”的缩写。
sinc函数用于各种信号处理应用中,包括抗锯齿,Lanczos重采样滤波器的构造和插值。
对于离散时间信号的带限内插,理想内插核与sinc函数成比例。
参考文献
[R282] Weisstein,Eric W.“Sinc Function。”来自MathWorld-Wolfram Web资源。http://mathworld.wolfram.com/SincFunction.html [R283] 维基百科,“Sinc函数”,http://en.wikipedia.org/wiki/Sinc_function 例子
>>> x = np.linspace(-4, 4, 41) >>> np.sinc(x) array([ -3.89804309e-17, -4.92362781e-02, -8.40918587e-02, -8.90384387e-02, -5.84680802e-02, 3.89804309e-17, 6.68206631e-02, 1.16434881e-01, 1.26137788e-01, 8.50444803e-02, -3.89804309e-17, -1.03943254e-01, -1.89206682e-01, -2.16236208e-01, -1.55914881e-01, 3.89804309e-17, 2.33872321e-01, 5.04551152e-01, 7.56826729e-01, 9.35489284e-01, 1.00000000e+00, 9.35489284e-01, 7.56826729e-01, 5.04551152e-01, 2.33872321e-01, 3.89804309e-17, -1.55914881e-01, -2.16236208e-01, -1.89206682e-01, -1.03943254e-01, -3.89804309e-17, 8.50444803e-02, 1.26137788e-01, 1.16434881e-01, 6.68206631e-02, 3.89804309e-17, -5.84680802e-02, -8.90384387e-02, -8.40918587e-02, -4.92362781e-02, -3.89804309e-17])
>>> plt.plot(x, np.sinc(x)) [<matplotlib.lines.Line2D object at 0x...>] >>> plt.title("Sinc Function") <matplotlib.text.Text object at 0x...> >>> plt.ylabel("Amplitude") <matplotlib.text.Text object at 0x...> >>> plt.xlabel("X") <matplotlib.text.Text object at 0x...> >>> plt.show()
它也工作在2-D:
>>> x = np.linspace(-4, 4, 401) >>> xx = np.outer(x, x) >>> plt.imshow(np.sinc(xx)) <matplotlib.image.AxesImage object at 0x...>