dysys 0.1.5

A package for working with system dynamics symbolically and numerically

DySys

A Python package for system dynamics and control systems utilities (using numpy, sympy, and control)

Installation

This package now published on PyPI and can be installed with

pip install dysys

Usage

To import the package into a script, use

import dysys as ds

Symbolic State-Space Models

Create a symbolic state-space model:

A = [[-4, -3, 0], [0, -8, 4], [0, 0, -1]]
B = [[0], [1], [0]]
C = [[0, 1, 0]]
D = [[0]]
sys = ds.sss(A, B, C, D)  # Create a symbolic state-space model

Factoring a Transfer Function

import dysys as ds
import control
import matplotlib.pyplot as plt

Define a transfer function using the dysys package as follows:

H = ds.tf(
    [1_000_000, 300_000_000],  # Numerator coef's
    [1, 1030, 40200, 10_300_000, 100_000_000]  # Denominator coef's
)

Get a list of transfer functions that are the canonical factors of H{.py}:

factors = H.factor_canonical(check=True)  # Check that the factors are correct

Print the factors:

for factor in factors:
    print(factor)

$\frac{3}{1}$
$\frac{0.003333 s + 1}{1}$
$\frac{1 \times 10^{4}}{s^2 + 20 s + 1 \times 10^{4}}$
$\frac{1}{0.1 s + 1}$
$\frac{1}{0.001 s + 1}$

Generate a Bode plot:

control.bode_plot([H] + factors, dB=True, wrap_phase=True)
plt.gcf().legend(
    list(map(lambda x: x._repr_latex_()[1:-1], [H] + factors)), 
    loc="outside center right",
)
plt.show()

Issues

If you have issues, please report them on the issues page.