Nested for loop needed

Question

Sun Kyoo Choi 2020-3-7

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/509636-nested-for-loop-needed

关闭： MATLAB Answer Bot 2021-8-20

Hi, I am trying to use nested for loop resuly(K),Ms(K), and Temp(i)

p1 = [6.78,2.79,9.8,11.93,7.81,8.83,5.81,12.85,10.94,7.84,5.29,4.83,9.77];
T1 = [23,23,22.5,23,22,22,22,22.5,22.5,22.5,24.5,22.5,24];
for K = 1:length(p1)
    for i = 1:length(T1)
p4 = 29.85;
fun = @(p2) p2/p4*(1 -((gamma-1)*(p2/p1(K)-1))./(2*gamma*(2*gamma+(gamma+1)*(p2/p1(K)-1))).^.5).^(-2.*gamma./(gamma-1))-1;
result(K) = fzero(fun,10)/p1(K) ;
Ms(K) = sqrt (((gamma+1)/(2.*gamma))*(result(K)-1)+1);
fun1 = @(T2) (result(K)*T1(i)/T2)*(((gamma+1)/(gamma-1))+result(K))/(1+(((gamma+1)/(gamma-1))*result(K)))-1;
Temp(i) = fzero(fun1,10);
    end
    
end 
%However, it somehow finds untill 8th column of result(K) and Ms(K) and cannot even find Temp(i). 
%It gives me an error of this "Function value at starting guess must be finite and real" for Temp(i) = fzero(fun1,10).
%So, I was wondering how I could fix to obtain every value [1x13] for result(K), Ms(K), and Temp(i). 

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Sun Kyoo Choi 2020-3-7

gamma is 1.4 fixed.

darova 2020-3-7

在 MATLAB Online 中打开

Try to change initial guess (increase)

result(K) = fzero(fun,p1(K)+10)/p1(K) ;

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Answer 1

Walter Roberson 2020-3-7

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/509636-nested-for-loop-needed#answer_419059

在 MATLAB Online 中打开

p1 = [6.78,2.79,9.8,11.93,7.81,8.83,5.81,12.85,10.94,7.84,5.29,4.83,9.77];
T1 = [23,23,22.5,23,22,22,22,22.5,22.5,22.5,24.5,22.5,24];
fun_guess = 20;
fun1_guess = 10;
for K = 1:length(p1)
    for i = 1:length(T1)
p4 = 29.85;
fun = @(p2) p2/p4*(1 -((gamma-1)*(p2/p1(K)-1))./(2*gamma*(2*gamma+(gamma+1)*(p2/p1(K)-1))).^.5).^(-2.*gamma./(gamma-1))-1;
result(K) = fzero(fun,fun_guess)/p1(K) ;
Ms(K) = sqrt (((gamma+1)/(2.*gamma))*(result(K)-1)+1);
fun1 = @(T2) (result(K)*T1(i)/T2)*(((gamma+1)/(gamma-1))+result(K))/(1+(((gamma+1)/(gamma-1))*result(K)))-1;
Temp(i) = fzero(fun1,fun1_guess);
    end
end 

However, notice that each iteration of for i you write into Temp(i) which is a location independent of K, so for example Temp(7) would reflect only the last time Temp was written into, when K was the final value. You are not saving Temp for each combination of p1 and T1.

Likewise you write to result(K) and Ms(K) independent of the value of i, so for any given K value, the value saved in result or Ms will reflect only the value written there on the last for i iteration. You are not saving result or MS for each combination of p1 and T1.