my error when i wrote that x*x or x^2 is not working

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Mohammed AL Rashedi 2023-3-3

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https://ww2.mathworks.cn/matlabcentral/answers/1922670-my-error-when-i-wrote-that-x-x-or-x-2-is-not-working

评论： Mohammed AL Rashedi 2023-3-3

n=1:100;
x=0:1;
for i=1:length(n)
  x^2 = mod(x,n(i));
Incorrect use of '=' operator. Assign a value to a variable using '=' and compare values for equality using '=='.
end
i want to get all value of n where x=0 And x = 1 onnnllly

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Voss 2023-3-3

"is true whene n = 7,25,13,...."

What's true when n = 7, 25, 13, ...?

What are you actually trying to do?

Mohammed AL Rashedi 2023-3-3

编辑：Mohammed AL Rashedi 2023-3-3

Now , let x^2 = x mod 7 then we have only two solution x=0 and x=1.

Simillary ,

let x^2 = x mod 25 then we have only two solution x=0 and x=1.

so now i want to conversely.

let there are two solutions x=0 and x=1 (only) i want to get n (n=7 ,n=25,.....)

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采纳的回答

Voss 2023-3-3

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https://ww2.mathworks.cn/matlabcentral/answers/1922670-my-error-when-i-wrote-that-x-x-or-x-2-is-not-working#answer_1184835

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Maybe this:

n=1:100;
n_true = [];
for i=1:length(n)
    x = 2:n(i)-1;
    x2 = mod(x.^2,n(i));
    if ~any(x2 == x)
        n_true(end+1) = n(i);
    end
end
disp(n_true);
  Columns 1 through 33

     1     2     3     4     5     7     8     9    11    13    16    17    19    23    25    27    29    31    32    37    41    43    47    49    53    59    61    64    67    71    73    79    81

  Columns 34 through 36

    83    89    97