MATLAB Answers

For Loop plot range of numbers

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Hailey
Hailey on 28 Nov 2019
Commented: Star Strider on 28 Nov 2019
Hello,
I'm trying to plot this equation:
Then use gamma as 1.4, 1.3, and 1.2.
And have n_n (eta_n) as a varied range of numbers: [ 1.00 0.975 0.975 0.950 0.925]
But with the code I kept trying to manipulate, I keep getting just one plot, and it's the wrong plot as well. Please, any advise will help.
the graph is supposed to be including all the eta_n. Each of them. Then the varied gammas are seperate. So, I should end up with three graphs, one for each gamma value, each having four curves (eta_n)
The graph is supposed to look like something like this: (if gamma = 1.3)
Capture.PNG
%gamma
g1 = 1.4;
g2 = 1.3;
g3 = 1.2;
%eta_n
n = [1.00 0.975 0.975 0.950 0.925];
%pt2/p_inf
p = 100;
%Me
M = linspace(1,10,15);
%Ae/A* for g = 1.4
for N = 1:numel(n)
A_1(n) = ((1./M).*((2/(g1+1)).*(1+((g1-1)./2).*M.^2).^((1/2).*((g1+1)./(g1-1))))).*((1+(1-(1./(n))).*((g1-1)./2).*M.^2).^(-g1/(g1-1)));
hold on
loglog(A_1(n),M);
xlabel('A_e/A*');
ylabel('M_e');
grid on
legend('eta_n=1.00','eta_n=0.975','eta_n=0.950','eta_n=0.925');
end

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Answers (2)

Star Strider
Star Strider on 28 Nov 2019
I cannot follow what you are doing.
At the very least, the ‘A_1’ assignment needs to be:
A_1(N,:) = ((1./M).*((2/(g1+1)).*(1+((g1-1)./2).*M.^2).^((1/2).*((g1+1)./(g1-1))))).*((1+(1-(1./(n(N)))).*((g1-1)./2).*M.^2).^(-g1/(g1-1)));
so the entire code becomes:
%gamma
g1 = 1.4;
g2 = 1.3;
g3 = 1.2;
gv = [g1, g2, g3]; % Optional, If You Want To Cycle Through Them Later
%eta_n
n = [1.00 0.975 0.975 0.950 0.925];
%pt2/p_inf
p = 100;
%Me
M = linspace(1,10,15);
%Ae/A* for g = 1.4
for N = 1:numel(n)
A_1(N,:) = ((1./M).*((2/(g1+1)).*(1+((g1-1)./2).*M.^2).^((1/2).*((g1+1)./(g1-1))))).*((1+(1-(1./(n(N)))).*((g1-1)./2).*M.^2).^(-g1/(g1-1)));
hold on
loglog(A_1(N,:),M);
xlabel('A_e/A*');
ylabel('M_e');
grid on
legend('eta_n=1.00','eta_n=0.975','eta_n=0.950','eta_n=0.925');
end
That produces one Warning about the legend entries, and otherwise runs without error.

  3 Comments

Hailey
Hailey on 28 Nov 2019
Hi,
Your code comes out as the below graph. I had this show up before for me too.Capture.PNG
Hailey
Hailey on 28 Nov 2019
Look at my question edit, and maybe that could help?
Star Strider
Star Strider on 28 Nov 2019
I cannot detect any errors in your code (or my edit of it).
There is obviously something ‘over the horizon’ that we can’t see.
I will delete my Answer later, since it does not appear to be one.

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Andrei Bobrov
Andrei Bobrov on 28 Nov 2019
g = reshape(1.4:-.1:1.2,1,1,[]);
n = [1.00, 0.975, 0.975, 0.950, 0.925];
M = linspace(1,10,15)';
g1 = g + 1;
g_1 = g - 1;
A = 1./M.*(2./g1.*(1+g_1./2.*M.^2)).^(.5*g1./g_1).*(1+(1-1./n).*g_1/2.*M.^2).^(-g./g_1);

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Hailey
Hailey on 28 Nov 2019
Hi Andrei,
Where would I submit this edit in my current code? Woud it go before the for loop? Thanks in advance.

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