Why isnt plot working for this code?

Question

Rithwik Jayanth 2021-10-25

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1571298-why-isnt-plot-working-for-this-code

回答： Star Strider 2021-10-25

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');

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VBBV 2021-10-25

You dont need a for loop for your code

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Answer 1

VBBV 2021-10-25

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1571298-why-isnt-plot-working-for-this-code#answer_815953

在 MATLAB Online 中打开

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

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Rithwik Jayanth 2021-10-25

Thank you so much!

Rithwik Jayanth 2021-10-25

one question

Why didnt it work with the for loop?

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Answer 2

Star Strider 2021-10-25

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1571298-why-isnt-plot-working-for-this-code#answer_816003

在 MATLAB Online 中打开

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.

.

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