Why isnt plot working for this code?

Hi, Im a still new to MatLab. I am not sure why the plot function is not plotting anything for my code

p = 0.002378*(1-0.0000068756*2000)^4.2561;

v=100;

AR = 7;

q = 0.5*p*v^2;

n = 1/cos(45);

e = 1.78*(1-0.045*AR^0.68)-0.64;

k = 1/(3.14*AR*e);

Vv = 25;

Vlof = 65;

u = 0.04;

g = 9.81;

Cdmin = 0.025;

Sg = 1000;

Clto = 0.5;

Cdto = 0.04;

figure

for WS = 0:70

TW1 = Vv/v + q/WS*Cdmin + k/q*WS;

TW2 = Vlof^2/(2*g*Sg) + q*Cdto/WS + u*(1-q*Clto/WS);

TW3 = q*(Cdmin/WS + k*(n/q)^2*WS);

% TW4 = q*(Cdmin/WS + k*(n/q)^2*WS) + Ps/V;

TW5 = q*Cdmin/WS + k/q*WS;

TW6 = Vv/sqrt(2/p*WS * sqrt(3/(3*Cdmin))) + 4*sqrt(k*Cdmin/3);

%plot(TW1,WS,'g',TW2,WS,'b',TW3,WS,'r',TW4,WS,'m',TW5,WS,'k',TW6,WS);

hold on

plot(WS,TW1,'g',WS,TW2,'b',WS,TW3,'r',WS,TW5,'k',WS,TW6,'y');

end

hold off

xlabel('W/S');

ylabel('T/W');

[VBBV]

You dont need a for loop for your code

Answer 1

[VBBV]

p = 0.002378*(1-0.0000068756*2000)^4.2561;
v=100;
AR = 7;
q = 0.5*p*v^2;
n = 1/cos(45);
e = 1.78*(1-0.045*AR^0.68)-0.64;
k = 1/(3.14*AR*e);
Vv = 25; 
Vlof = 65;
u = 0.04;
g = 9.81;
Cdmin = 0.025;
Sg = 1000;
Clto = 0.5;
Cdto = 0.04;
figure
WS = 0:70;
    TW1 = Vv/v + q./WS*Cdmin + k./q*WS;
    TW2 = Vlof^2/(2*g*Sg) + q*Cdto./WS + u*(1-q*Clto./WS);
    TW3 = q*(Cdmin./WS + k*(n/q)^2.*WS);   
    TW5 = q*Cdmin./WS + k./q*WS;
    TW6 = Vv./sqrt(2./p*WS * sqrt(3/(3*Cdmin))) + 4*sqrt(k*Cdmin/3);       
    plot(WS,TW1,'g',WS,TW2,'b',WS,TW3,'r',WS,TW5,'k',WS,TW6,'y');
    
%hold off
xlabel('W/S');
ylabel('T/W');
legend

[Rithwik Jayanth]

Thank you so much!

[Rithwik Jayanth]

one question

Why didnt it work with the for loop?

Answer 2

[Star Strider]

It will work with the for loop if (1) the plot call plots points instead of lines, or (2) if the values are subscripted inside the loop and plotted afterwards. This is because plot plots lines between points, not points themsleves, so either define markers or create vectors for the variables.

Plotting points —

p = 0.002378*(1-0.0000068756*2000)^4.2561;
v=100;
AR = 7;
q = 0.5*p*v^2;
n = 1/cos(45);
e = 1.78*(1-0.045*AR^0.68)-0.64;
k = 1/(3.14*AR*e);
Vv = 25; 
Vlof = 65;
u = 0.04;
g = 9.81;
Cdmin = 0.025;
Sg = 1000;
Clto = 0.5;
Cdto = 0.04;
figure
for WS = 0:70
    TW1 = Vv/v + q/WS*Cdmin + k/q*WS;
    TW2 = Vlof^2/(2*g*Sg) + q*Cdto/WS + u*(1-q*Clto/WS);
    TW3 = q*(Cdmin/WS + k*(n/q)^2*WS);
    % TW4 = q*(Cdmin/WS + k*(n/q)^2*WS) + Ps/V;
    TW5 = q*Cdmin/WS + k/q*WS;
    TW6 = Vv/sqrt(2/p*WS * sqrt(3/(3*Cdmin))) + 4*sqrt(k*Cdmin/3);
    
    %plot(TW1,WS,'g',TW2,WS,'b',TW3,WS,'r',TW4,WS,'m',TW5,WS,'k',TW6,WS);
    hold on
    plot(WS,TW1,'.g',WS,TW2,'.b',WS,TW3,'.r',WS,TW5,'.k',WS,TW6,'.y');
    
end
hold off
xlabel('W/S');
ylabel('T/W');

Plotting vectors —

p = 0.002378*(1-0.0000068756*2000)^4.2561;
v=100;
AR = 7;
q = 0.5*p*v^2;
n = 1/cos(45);
e = 1.78*(1-0.045*AR^0.68)-0.64;
k = 1/(3.14*AR*e);
Vv = 25; 
Vlof = 65;
u = 0.04;
g = 9.81;
Cdmin = 0.025;
Sg = 1000;
Clto = 0.5;
Cdto = 0.04;

WSv = 0:70;
for k1 = 1:numel(WSv)
    WS = WSv(k1);
    TW1(k1) = Vv/v + q/WS*Cdmin + k/q*WS;
    TW2(k1) = Vlof^2/(2*g*Sg) + q*Cdto/WS + u*(1-q*Clto/WS);
    TW3(k1) = q*(Cdmin/WS + k*(n/q)^2*WS);
    % TW4 = q*(Cdmin/WS + k*(n/q)^2*WS) + Ps/V;
    TW5(k1) = q*Cdmin/WS + k/q*WS;
    TW6(k1) = Vv/sqrt(2/p*WS * sqrt(3/(3*Cdmin))) + 4*sqrt(k*Cdmin/3);
    
    %plot(TW1,WS,'g',TW2,WS,'b',TW3,WS,'r',TW4,WS,'m',TW5,WS,'k',TW6,WS);
    
end

figure
plot(WSv,TW1,'g',WSv,TW2,'b',WSv,TW3,'r',WSv,TW5,'k',WSv,TW6,'y');
xlabel('W/S');
ylabel('T/W');

Experiment to get different results.

.