Matlab: System response query.

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Discussion Overview

The discussion revolves around a Matlab problem related to finding the system response of a transfer function given a unit step input and zero initial conditions. Participants are examining the correct formulation of the transfer function's numerator and denominator.

Discussion Character

  • Homework-related

Main Points Raised

  • One participant presents a transfer function G(s) = 1/(s+5) and attempts to use Matlab to find the system response.
  • Another participant points out that the denominator is incorrect, suggesting it should be den = [1 5].
  • A third participant questions whether the correct denominator should be [1 -5] and seeks confirmation on the overall correctness of the approach.
  • A fourth participant clarifies that Matlab does not build transfer functions based on their roots, indicating that the arrays provided should represent coefficients of the Laplace polynomial.

Areas of Agreement / Disagreement

Participants express differing views on the correct formulation of the denominator for the transfer function, indicating that there is no consensus on this aspect of the problem.

Contextual Notes

There are unresolved issues regarding the correct coefficients for the transfer function's denominator and the implications of these choices on the Matlab implementation.

technowar
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Homework Statement


Hi. I need help on this Matlab problem.

I need to find the system response of the function, where the input is a unit step and a zero initial condition.

G(s) = 1/(s+5)

Homework Equations



G(s)=C(s)/R(s)

The Attempt at a Solution



num=[1];
den=[-5];
t=0:0.1:80;
step(num,den,t)

[PLAIN]http://cl.ly/3G0U3g473B1Y0L1r2d2o/1.jpg
 
Last edited by a moderator:
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Your denominator is incorrect, it should be den = [1 5] basically the transfer function should look like G(s) identically
 
Shouldn't it be [1 -5]? But other than that, do you think it's correct?
 
No MATLAB does not build transfer functions according to their roots. The arrays you provide are coefficient to the laplace polynomial.
 

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