how do i check if a number is a prime number, a square, and or a factor of 6?

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Vjon Joson 2020-4-1

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https://ww2.mathworks.cn/matlabcentral/answers/514501-how-do-i-check-if-a-number-is-a-prime-number-a-square-and-or-a-factor-of-6

编辑： DGM 2023-1-5

采纳的回答： Birdman

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here is the current idea for the code so far

integer = 4;
if % ** check if integer is a prime **
    Prime = integer % => If condition is met
elseif % ** check if the number is square **
    Square = integer % => Else condition is met
elseif % chekc if divisible by 6
Factorof6=integer
end

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Walter Roberson 2023-1-5

https://www.mathworks.com/matlabcentral/answers/514501-how-do-i-check-if-a-number-is-a-prime-number-a-square-and-or-a-factor-of-6#comment_819187

DGM 2023-1-5

编辑：DGM 2023-1-5

在 MATLAB Online 中打开

Since the core answers are all basically already on this page, I'll just add that logical indexing, implicit casting, and implicit expansion can make this tidy.

x = 100:999; % a set of numbers as a row vector
issquare = ~mod(sqrt(x),1); % implicit binarization
ismultiple = ~mod(x,[2; 3; 5]); % implicit expansion
validnums = issquare & ~any(ismultiple,1); % logical combination of masks
x(validnums) % logical indexing
ans = 1×7
   121   169   289   361   529   841   961

Now you have to make a function out of it.

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采纳的回答

Birdman 2020-4-1

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n=4;
%check if number is prime
isprime(n) %returns logical value
%check if number is square
mod(numel(factor(n)),2)==0 %returns logical value
%check if number is divisible by 6
mod(n,6)==0 %returns logical value

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Torsten 2022-10-15

编辑：Torsten 2022-10-15

2*3 = 6, and 6 is not a square.

Yes, the answer given is incorrect.

mod(numel(factor(a)),2)==0 is not sufficient for "a" to be a square.

Walter Roberson 2022-10-16

https://www.mathworks.com/matlabcentral/answers/514501-how-do-i-check-if-a-number-is-a-prime-number-a-square-and-or-a-factor-of-6#comment_819105 shows a revised test (which I did not examine)

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