object orianted programing (OOP ) cant understand

hello I started to learn progrmaing withh oop becouse me coude became too long , now i have problems understandg how to use it correctly for exmpale i have this code :

classdef main_code_oop
 properties 
f; 
U;C;C1;L2;L1;R_C;R_C1;R1;R2;R_diode;V_diode;Duty_cycle;alpha;
 end 
methods 

      function variable=main_code_oop()
     variable.U=12;    
     variable.f=30e3;
     variable.C=2200e-6;
     variable.C1=470e-6;
     variable.L1=1e-3;
     variable.L2=1e-3;
     variable.R_C=0.05;
     variable.R_C1=0.1;
     variable.R1=0.1;
     variable.R2=0.1;
     variable.R_diode=0.00000000000001;
     variable.V_diode=0.3;
     variable.Duty_cycle=62.5;
     Duty_cycle=variable.Duty_cycle;
     end

     function [alpha]=Calculating_alpha(Duty_cycle)

   alpha=(1-(Duty_cycle/100))/(Duty_cycle/100);

     end

 end

how can i see alpha in the command space ? and to cheak if i got the right answer ?

[SL: edited to apply code formatting]

Answer 1

[Steven Lord]

The Calculating_alpha method of your main_code_oop object must accept an instance of the object main_code_oop, not a numeric value like the value of one of the object's properties.

function alpha = Calculating_alpha(myObject)
end

Now inside the method you can access properties of the object.

function alpha = Calculating_alpha(myObject)
  alpha=(1-(myObject.Duty_cycle/100))/(myObject.Duty_cycle/100);
end

If you want you can extract a property you're going to use repeatedly into a variable, so you don't have to fetch it from the object over and over again.

function alpha = Calculating_alpha(myObject)
  DC = myObject.Duty_cycle;
  alpha=(1-(DC/100))/(DC/100);
end

Now to call that method, instantiate (create) an instance of the object and pass it into the method.

q = main_code_oop;
A = Calculating_alpha(q)

Answer 2

[OCDER]

Here are some suggestions for improving the code. See the comments in %.

classdef main_code_oop < handle %make handle the superclass to allow you to modify properties like obj.alpha = 2. 
    properties (GetAccess = public) %public means outside command CAN modify these variables
        f;          %Write description
        U;          %Write description
        C;          %Write description
        C1;         %Write description
        L2;         %Write description
        L1;         %Write description
        R_C;        %Write description
        R_C1;       %Write description
        R1;         %Write description
        R2;         %Write description
        R_diode;    %Write description
        V_diode;    %Write description
        Duty_cycle; %Write description
    end

      properties (GetAccess = private) %private means outside commands cannot modify alpha
          alpha;      %Write description
      end    

      methods
          function variable = main_code_oop()
              variable.U=12;    
              variable.f=30e3;
              variable.C=2200e-6;
              variable.C1=470e-6;
              variable.L1=1e-3;
              variable.L2=1e-3;
              variable.R_C=0.05;
              variable.R_C1=0.1;
              variable.R1=0.1;
              variable.R2=0.1;
              variable.R_diode=0.00000000000001;
              variable.V_diode=0.3;
              variable.Duty_cycle=62.5;
              %Duty_cycle=variable.Duty_cycle; %This is unused
          end

          %- Instead of using LONG words like "Calculating_alpha", use short verb + Description. 
          %    Makes life easier and it's the standard in OOP.
          %    EX: calcAlpha, getAlpha, setAlpha
          %- Pass the object as input, not Duty_cycle
          %function [alpha] = Calculating_alpha(Duty_cycle)
          function [alpha] = calcAlpha(obj)
              alpha = (1-(obj.Duty_cycle/100))/(obj.Duty_cycle/100);
              obj.alpha = alpha;   %Updates private property, alpha
          end

          %In case you want to get access to a private property
          function [alpha] = getAlpha(obj)
              alpha = obj.alpha;
          end
      end
   end