Store values from a for loop in matrix and plot them.

I'm sure there's a better way to do this but i'm not sure how to go about it. I'm trying to store the values from my for loops into matrix, and trying to plot it after. So far it just gives me all the values in a 1*1 matrix and try to plot just one value ( which doesn't even shows up on the graph). I don't see any errors that pops up .

R=287;
Qr=43400000;   %heat reaction value
Pa=187500;     % atmospher
Ta=216.7;    % outside temprature
M=.73;         % mach number
gd=1.4;         %gama

% variables 
B=5;           %bypass ratio
To4=1875;      %turbine inlet temperature

%Prf= not given;    %Fan pressure ratio

%Efficiencies and gamma for specific heat
d=.97;            gamad=1.4;            %diffuser
c=.85;            gamac=1.37;           %compressor
b=1;              gamab=1.35;           %burner
t=.9;             gamat=1.33;           %turben 
nz=.98;           gamanz=1.36;          %nozzle
fan=.85;          fangamenz=1.4;        %fan
fan_nozzle=.97;                         %fan nozzle




%flight velocity equation
U=M*sqrt(gd*R*Ta);
%compressor inlet temperature calculation
T0a=Ta*(1+(gamad-1)/2*M^2);
T02=T0a;
%compressor inlet pressure calculation
P02=Pa*(1+d*(T02/Ta-1))^(gd/(gd-1));

%compressor outlet pressure calculation
 

for    Prc=7:1:27 ;   %compressor ratio
        P03=P02*Prc;
        P04=P03;
        %compressor outlet temperature calculation
        T03=T02*(1+1/c*(Prc^((gamac-1)/gamac)-1));

        %Cp calculations
        Cpb=(gamab/(gamab-1))*R;
        Cpc=(gamac/(gamac-1))*R;
        Cpt=(gamat/(gamat-1))*R;
        %fuel to air flow rate ratio
        f=(To4-T03)/(Qr/Cpb-To4);
        
        %fan pressure ratio
  Prf=1;  % i start with one so i can put in a loop after
        
  
        %fan pressure and temperature calculation
        P08=P02*Prf;
        T08=T02*(1+1/fan*(Prf^((fangamenz-1)/fangamenz)-1));
        %turbine outlet condition calculations
        T05=To4-(T03-T02)-B*(T08-T0a);
        P05=P04*(1-1/t*(1-T05/To4))^(gamat/(gamat-1));
        %nozzle inlet conditions
        P06=P05;
        T06=T05;
        P05==P08;
        

        if P05==P08;
            continue 
        else 
            for Prf=1:001:2;
              
              P08=P02*Prf;
        T08=T02*(1+1/fan*(Prf^((fangamenz-1)/fangamenz)-1));
        %turbine outlet condition calculations
        T05=To4-(T03-T02)-B*(T08-T0a);
        P05=P04*(1-1/t*(1-T05/To4))^(gamat/(gamat-1));
        %nozzle inlet conditions
        P06=P05;
        T06=T05;
            end
        
            
        %exit flight velocities calculations
        Ue=sqrt(2*nz*gamanz/(gamanz-1)*R*T06*(1-(Pa/P06)^((gamanz-1)/gamanz)));
        Uef=sqrt(2*fan_nozzle*fangamenz/(fangamenz-1)*R*T08*(1-(Pa/P08)^((fangamenz-1)/fangamenz)));
        %specific thrust and TSFC calculations
        specthrust=(1+f)*Ue+B*Uef-(1+B)*U;
        %fprintf('your specific thrust is %f', specthrust)
       format bank
        %disp(num2str(specthrust,'%.0f'))
        TSFC=f/specthrust;
        format bank
        %disp(num2str(TSFC,'%.0f'));
        %overall efficiency calculations
        A=((1+f)*Ue^2/2+B*Uef^2/2-(1+B)*U^2/2);
        ep=specthrust*U/A;
        eth=A/(Qr*f);
        eoa=ep*eth;
        format bank
         %disp(num2str(eoa,'%.0f'));
         
   fprintf(' for Prc: %d\n', Prc)
fprintf('your specific thrust is %f', specthrust)      
figure(1)
plot(Prc,specthrust)
        end

end

Answer 1

[Chris]

You need an index to keep track of your loop iterations. You can do this one of two ways:

idx = 0
for Prc = Prc=7:1:27
idx = idx+1;
...
specthrust(idx) = (1+f)*Ue+B*Uef-(1+B)*U;
end

or

PrcArray = 7:1:27;
for idx = 1:numel(PrcArray)
    Prc = PrcArray(idx);
    ...
    specthrust(idx) = (1+f)*Ue+B*Uef-(1+B)*U;
end

Then you should be able to plot everything at once.

The reason the plot doesn't show up as it is is that plot() needs at least two x points and two y points to draw a line.

scatter() would be a better tool for plotting single points.

[Jerin Thomas]

That makes sense, that you need the idx. but why is it only plotting one one point? how can i make it scatter plot all of them on the same graph?

[Chris]

You would need to turn hold on, to prevent the plot from being overwritten.

figure(1)
hold on
for Prc = 7:27
    specthrust = sqrt(Prc);
    figure(1)
    scatter(Prc,specthrust,'b*');
end

To plot outside the loop, all you would need is the two vectors.

Prc = 7:27;
specthrust = sqrt(Prc);
figure
plot(Prc,specthrust,'*')

[Jerin Thomas]

Thank you!