change two variable in the name in a loop using eval or any other command

Hi I´m having a problem with this code:

HOw can I change both the M and N in the varibles of P_M_out_N names in a loop. Ithe following colud change N with loop

but I do not know how to change M values in the loop.

clc; clear all; close all
%P_M_out_N = u^j
u=3;
j=1:5;
M= [1 8 6 2  4];
N =[2 3 7 8 12]
for j = 1:length(M)
    eval(sprintf('M_out_of_%d=u^j', N(j)))
end
%%
 P_1_out_2 = u
 P_8_out_3 = u^2
 P_6_out_7=  u^3
 P_2_out_8 =  u^4
 P_4_out_12 =  u^5

[Stephen23]

Dynamically defining or accessing variable names is one way that beginners force themselves into writing slow, complex, obfuscated, buggy, hard-to-debug code. Read this to know why:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Not only that, but the including meta-data into variable names or fieldnames makes code slow, complex, and fragile. Read this to know why:

https://www.mathworks.com/matlabcentral/answers/225435-save-variable-as-string-from-user-input

In your case you can easily write much simpler, neater, more efficient code, just like experienced MATLAB users would:

>> u = 3;
>> M = [1,8,6,2,4];
>> N = [2,3,7,8,12];
>> V = u.^(1:numel(N))
V =
     3     9    27    81   243

and just then use basic MATLAB indexing to access the corresponding vector elements. Indexing is simple, neat, easy to debug, and very efficient (unlike what you are trying to do).

Answer 1

[madhan ravi]

I suggest you to use struct with dynamic field names ( https://blogs.mathworks.com/loren/2005/12/13/use-dynamic-field-references/ ) , using eval() is not a good idea ( https://in.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval )

for k=1:numel(M)
    s.(sprintf('P_%d_out_%d',M(k),N(k)))=u^k;
end

Answer 2

[Abdulmajid Mrebit]

Thank you very much