# Why isnt plot working for this code?

조회 수: 4(최근 30일)
Rithwik Jayanth 2021년 10월 25일
답변: Star Strider 2021년 10월 25일
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');
##### 댓글 수: 1표시숨기기 없음
VBBV 2021년 10월 25일
You dont need a for loop for your code

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### 답변(2개)

VBBV 2021년 10월 25일
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
##### 댓글 수: 2표시숨기기 이전 댓글 수: 1
Rithwik Jayanth 2021년 10월 25일
one question
Why didnt it work with the for loop?

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Star Strider 2021년 10월 25일
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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