how to code equation

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Cesar Cardenas
Cesar Cardenas on 3 Feb 2023
Commented: Walter Roberson on 17 Feb 2023
I'm trying to code these equations. This is my attempt. I would like to plot Cf vs x/L, but x/L as I have it shows me an error..the same with delta/x, not sure why? any help will be greatly appreciated. Thanks much.
Re = 0:500:1000;
x/L = 0:0.2:1;
Cf = 0.664*(Re)^-0.5;
delta/x = 5.0*(Re)^-0.5;
  1 Comment
Les Beckham
Les Beckham on 3 Feb 2023
Edited: Les Beckham on 3 Feb 2023
What are x, L, and delta?
Also, you can't put an expression like x/L on the left hand side of an assignment statement, only a variable name (optionally indexed).

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Accepted Answer

Sulaymon Eshkabilov
Sulaymon Eshkabilov on 3 Feb 2023
Here is the corrected code:
Re = 0:50:1000;
xL = linspace(0,1, numel(Re));
Cf = 0.664*(Re).^(-0.5);
deltaX = 5.0*(Re).^(-0.5);
plot(Cf, xL, 'ro', 'markerfacecolor', 'y')
grid on
Walter Roberson
Walter Roberson on 17 Feb 2023
Your h, q, and Re are all scalars, so plotting them on the same graph is not going to be interesting.
T1 = 30;
T2 = 40;
v = 0.5;
x1 = 0.01;
x2 = 0.05;
Pr = 5.18;
nu = 7.708;
k = 0.6184;
d = 995;
Re = v*(x2-x1)/nu
Re = 0.0026
h = 0.3314*(Re.^(0.5))*(Pr.^(0.3))*(k/x2 - x1)
h = 0.3417
q = h*(x2 - x1)*1*(T2-T1)
q = 0.1367
plot([h, q, Re],'r*')

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