`scipy.signal.windows._windows:flattop`

source: build-install/usr/lib/python3.14/site-packages/scipy/signal/windows/_windows.py:704

Signature

def flattop(M, sym = True, *, xp = None, device = None)

Summary

Return a flat top window.

Parameters

M : int: Number of points in the output window. If zero, an empty array is returned. An exception is thrown when it is negative.
sym : bool, optional: When True (default), generates a symmetric window, for use in filter design. When False, generates a periodic window, for use in spectral analysis.
xp : array_namespace, optional: Optional array namespace. Should be compatible with the array API standard, or supported by array-api-compat. Default: numpy
device : any: optional device specification for output. Should match one of the supported device specification in xp.

Returns

w : ndarray: The window, with the maximum value normalized to 1 (though the value 1 does not appear if M is even and sym is True).

Notes

Flat top windows are used for taking accurate measurements of signal amplitude in the frequency domain, with minimal scalloping error from the center of a frequency bin to its edges, compared to others. This is a 5th-order cosine window, with the 5 terms optimized to make the main lobe maximally flat. ^[1]

Examples

Plot the window and its frequency response:

import numpy as np
from scipy import signal
from scipy.fft import fft, fftshift
import matplotlib.pyplot as plt

✓

window = signal.windows.flattop(51)

✓

plt.plot(window)
plt.title("Flat top window")
plt.ylabel("Amplitude")
plt.xlabel("Sample")

✗

Text(0.5, 0, 'Sample')

plt.figure()

✗

<Figure size 640x480 with 0 Axes>

A = fft(window, 2048) / (len(window)/2.0)
freq = np.linspace(-0.5, 0.5, len(A))
response = 20 * np.log10(np.abs(fftshift(A / abs(A).max())))

✓

plt.plot(freq, response)
plt.axis([-0.5, 0.5, -120, 0])
plt.title("Frequency response of the flat top window")
plt.ylabel("Normalized magnitude [dB]")
plt.xlabel("Normalized frequency [cycles per sample]")

✗

Text(0.5, 0, 'Normalized frequency [cycles per sample]')

Aliases

scipy.signal.windows.flattop