MATLAB: Could you help me interpret what happened

MATLABobject oriented programming

Greetings,

I am debugging others' codes. In Polyhedron.m file row 521, it is a sentence:

if isempty(obj.He_int), obj.He_int = zeros(0,d+1); end

I found before this sentence was executed, obj.V was not defined as:

But after this sentence was executed, obj.V was calculated and got a matrix:

As you see, the sentence did not call obj.V directly but it did change obj.V. Could you explain to me what happened here? And how can I find the codes that changed obj.V. I think that is the bug I am looking for.

Related source codes are attached.

Thank you!

Best Answer

obj.V is a Dependent property.

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MATLAB: Writing “this” class’ properties

I'm just guessing at what you're trying to do, but here is a different version of your method:

function y=ChangeProperties(this,vnew)
  y = this;
  y.v=vnew;
end

Then if you run

a = agent_type(1);
a = a.ChangeProperties([0 0])

you get

a = 
agent_type
Properties:
   v: [0 0]
  id: 1

MATLAB: Object properties that automatically update but aren’t Depenent

function obj = set.P(obj,pressure)
    if ~isempty(obj.P)
        error('Pressure is already set, please change pressure via specific process')
    end
    obj.P = pressure;
    obj.V = obj.n*obj.Rbar*obj.T/pressure;
    obj.n = pressure*obj.V/obj.Rbar/obj.T;
    obj.T = pressure*obj.V/obj.n/obj.Rbar;
end

So obj.P will have the new pressure value. obj.V will be calculated using the old n, Rbar, and T and the new P. Then obj.n will be calculated using the new pressure and V and the old Rbar and T. Do you then need to go back and recalculate obj.V using the new pressure and n and the old Rbar and T?

Giving a new value for any of the parameters will have a ripple effect on the others. I probably wouldn't try to use property set methods but I might use property get methods. If you're concerned about recomputing one of the parameters using a lengthy calculation consider using a memoize object.

Best Answer

Related Solutions

MATLAB: Writing “this” class’ properties

MATLAB: Object properties that automatically update but aren’t Depenent

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