Undefined Variable in Matlab

The Following is the basic skeleton for my MATLAB program. Each box is a class definition.

Scroll down for the error.

The Error

Undefined function or variable 'Troom'.

Error in ==> wall>wall.wall at 31
        function o = wall(Tr)

Error in ==> mainfile at 5
        w1 = wall();

This comes when I create an object of Class wall from another file "mainfile"

Question

1. Why is this happening?
2. Am I getting wrong in the concepts of OOP for Matlab specific?
3. How do I resolve this?

Thanks in Advance!

PS: Code

function o = wall()
        Tr开发者_如何转开发 = o.Troom*2;
        o.N = round(1/o.dx) + 1;
        o.T = Tr * ones(o.N,1);
        o.Tinf = Tr;
        o.update_properties();
    end

Code 2

classdef wall
properties
    dx = 0.01;
    dt = 0.4;
    L = 0.16;
    N;
    tlimit = 1505.2;
    sbc = 5.670400e-8 % The Stefan-Boltzmann Constant

    a;
    hi; % Surface Conductivity of Inner Surface
    bi;
    ho; % Surface Conductivity of Outer Surface
    bo;
    lamb;

    Troom = 298; % Room Temperature (K)
    Tinf;
    T;

    room = compartment();
    conc = concrete();
    fire = fireProperties(Troom);

end

room = compartment();
conc = concrete();
fire = fireProperties(Troom);

Yeah, there's your problem right there. Troom can't be used in the context of the properties block. Either put the constant in for Troom or move these into the constructor where they belong.