the plot window appears but , no graphs , i am in a bad need to help here

Ts=90 ;

L=1 ;

b=0.5 ;

T=30 ;

U=1 ;

Tm=(Ts+T)/2 ;

A=L*b ;

Rcr=5*10^5 ;

K2=[0.140 , 0.654 , 0.29 , 0.96] ;

M2=[0.072 , 4.71*10^(-4) , 2*10^5 , 1.6*10^(-3)] ;

v2=[0.839*10^(-4) , 4.7*10^(-7) , 19*10^(6) , 10^(-6)] ;

Pr2=[1050 , 3.01 , 0.697 , 0.02] ;

for i=1:4

for X=0.0001:0.1:1

%For Plotting 1 Table 1

Xcr(i)=(Rcr*v2(i))/U ;

if X<Xcr(i)

Re2(i)=(U*X)./v2(i) ;

Nu2(i)=(0.332*(Re2(i)).^(1/2))*(Pr2(i)).^(1/3) ;

d2(i)=(5*X)./(Re2(i).^(1/2)) ;

dt2(i)=d2(i)/(Pr2(i).^(1/3)) ;

h2(i)=(K2(i)*Nu2(i))./X ;

Cf2(i)=0.664*Re2(i).^(-1/2) ;

else

 Re2(i)=(U*X)./v2(i) ;

 Nu2(i)=0.0296*((Re2(i)).^(4/5))*Pr2(i).^(1/3) ;

d2(i)=0.37*X.*Re2(i).^(-1/5) ;

dt2(i)=0.37*X.*Re2(i).^(-1/5) ;

h2(i)=(K2(i)*Nu2(i))./X ;

Cf2(i)=0.0592*Re2(i).^(-1/5) ;

end end end

plot (X,Cf2)

[Image Analyst]

I can't run it. What is Rcr?

Undefined function or variable 'Rcr'.
Error in test (line 22)
Xcr(i)=(Rcr*v2(i))/U ;

[mahmoud samy]

please reload , i had edit the code , the givens are written up there

[mahmoud samy]

found something !

Answer 1

[Star Strider]

Your problem is that in your plot call, ‘X’ is a single value (0.9), and

Cf2 =

        0.0064107    0.0032801       3050.7    0.0038147

You need to resolve that, since only you know what you want to do.

Be sure to check the values of the variables you are using as arguments to plot.

[mahmoud samy]

sir i appreciate your effort , but how can u say that "X" is just a single value (0.9) .. and i wrote that X=0.0001:0.1:1 ? ... do i miss something ?

[Star Strider]

My pleasure.

Apparently you did miss something. Just after the plot call, type in your script file:

X
Cf2

You will get the results I posted, if you used the same (edited) code you posted.

[mahmoud samy]

where is my mistake then .. i wanted every value of i , to pass on every single value of X within the "if" condition , so i wrote X as i did .. how can i solve it?? .. thank u any way sir

[Star Strider]

I have no idea what you want to do with your code, so I can’t help you with that.

Do your calculations step-wise. Look at each calculation, see if it produces the result you want, and correct it if it does not. Use the debugging functions in MATLAB, or just remove the semicolons from the ends of each statement in turn until you find the problem.

Once you find the problem, if you cannot figure out the solution of the problem yourself, post the relevant parts of your code, what you want it to produce and what it produces. We can help you then.

We absolutely cannot guess what you are thinking!

Answer 2

[Image Analyst]

Try this:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;

Ts=90;
L=1;
b=0.5;
T=30;
U=1;
Tm=(Ts+T)/2;
A=L*b;
Rcr=5*10^5;
K2=[0.140 , 0.654 , 0.29 , 0.96];
M2=[0.072 , 4.71*10^(-4) , 2*10^5 , 1.6*10^(-3)];
v2=[0.839*10^(-4) , 4.7*10^(-7) , 19*10^(6) , 10^(-6)];
Pr2=[1050 , 3.01 , 0.697  , 0.02];
for i=1:4
  for X=0.0001:0.1:1
    %For Plotting 1   Table 1
    Xcr(i)=(Rcr*v2(i))/U;
    if  X<Xcr(i)
      Re2(i)=(U*X)./v2(i);
      Nu2(i)=(0.332*(Re2(i)).^(1/2))*(Pr2(i)).^(1/3);
      d2(i)=(5*X)./(Re2(i).^(1/2));
      dt2(i)=d2(i)/(Pr2(i).^(1/3));
      h2(i)=(K2(i)*Nu2(i))./X;
      Cf2(i)=0.664*Re2(i).^(-1/2);
    else
      Re2(i)=(U*X)./v2(i);
      Nu2(i)=0.0296*((Re2(i)).^(4/5))*Pr2(i).^(1/3);
      d2(i)=0.37*X.*Re2(i).^(-1/5);
      dt2(i)=0.37*X.*Re2(i).^(-1/5);
      h2(i)=(K2(i)*Nu2(i))./X;
      Cf2(i)=0.0592*Re2(i).^(-1/5);
    end
  end
end
plot (Cf2, 'b-', 'LineWidth', 2)
xlabel('Index of Cf2', 'FontSize', 22);
ylabel('Cf2', 'FontSize', 22);
grid on;