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## PathSim example of an algebraic loop

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# IMPORTS ===============================================================================

import numpy as np

import matplotlib.pyplot as plt

from pathsim import Simulation, Connection

from pathsim.blocks import (

Source,

Amplifier,

Adder,

Scope,

)

# ALGEBRAIC LOOP ========================================================================

#simulation timestep

dt = 0.1

#algebraic feedback

a = -0.2

#blocks that define the system

Src = Source(lambda t: 2*np.cos(t))

Amp = Amplifier(a)

Add = Adder()

Sco = Scope(labels=["src", "amp", "add"])

blocks = [Src, Amp, Add, Sco]

#the connections between the blocks

connections = [

Connection(Src, Add),

Connection(Add, Amp),

Connection(Amp, Add[1]),

Connection(Src, Sco),

Connection(Amp, Sco[1]),

Connection(Add, Sco[2])

]

#initialize simulation with the blocks, connections, timestep and logging enabled

Sim = Simulation(blocks, connections, dt=dt, log=True)

# Run Example ===========================================================================

if __name__ == "__main__":

#run the simulation for some time

Sim.run(5)

Sco.plot(".-")

plt.show()