scipy.signal.

bode

scipy.signal.bode(system, w=None, n=100)

Calculate Bode magnitude and phase data of a continuous-time system.

Parameters:

systeman instance of the LTI class or a tuple describing the system.

The following gives the number of elements in the tuple and the interpretation:

• 1 (instance of lti)

• 2 (num, den)

• 3 (zeros, poles, gain)

• 4 (A, B, C, D)

warray_like, optional

Array of frequencies (in rad/s). Magnitude and phase data is calculated for every value in this array. If not given a reasonable set will be calculated.

nint, optional

Number of frequency points to compute if w is not given. The n frequencies are logarithmically spaced in an interval chosen to include the influence of the poles and zeros of the system.

Returns:

w1D ndarray

Frequency array [rad/s]

mag1D ndarray

Magnitude array [dB]

phase1D ndarray

Phase array [deg]

Notes

If (num, den) is passed in for system, coefficients for both the numerator and denominator should be specified in descending exponent order (e.g. s^2 + 3s + 5 would be represented as [1, 3, 5]).

Added in version 0.11.0.

Array API Standard Support

bode has experimental support for Python Array API Standard compatible backends in addition to NumPy. Please consider testing these features by setting an environment variable SCIPY_ARRAY_API=1 and providing CuPy, PyTorch, JAX, or Dask arrays as array arguments. The following combinations of backend and device (or other capability) are supported.

Library	CPU	GPU
NumPy	✅	n/a
CuPy	n/a	✅
PyTorch	✅	✅
JAX	✅	✅
Dask	✅	n/a

See Support for the array API standard for more information.

Examples

Try it in your browser!

>>> from scipy import signal
>>> import matplotlib.pyplot as plt

>>> sys = signal.TransferFunction([1], [1, 1])
>>> w, mag, phase = signal.bode(sys)

>>> plt.figure()
>>> plt.semilogx(w, mag)    # Bode magnitude plot
>>> plt.figure()
>>> plt.semilogx(w, phase)  # Bode phase plot
>>> plt.show()

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