How can I display prime numbers with their number of order?

Question

Tayfun Aydogmus 2021-5-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/824630-how-can-i-display-prime-numbers-with-their-number-of-order

评论： Tayfun Aydogmus 2021-5-10

Hello everyone,

I'm quite new to Matlab and was working on a code to display prime numbers between 2 and an user defined input. Now I wanna make "a little" change by showing the user not only all the prime numbers between 2 and the users input but also the number of order for each prime number like this for example.

User Input = 10

Output:

2
3
5
7

My question would be how can I do this with my current code

limit = input('Prime numbers up to : ');

if limit == 1

disp('Please enter a number greater than 2!')

end

for n = 2:limit

identDivisor = logical(false);

k = 2;

while k < floor(sqrt(n))+1 && identDivisor == false

if mod(n,k) == 0

identDivisor = true;

end

k = k + 1;

end

if identDivisor == false

disp(n)

end

return

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Answer 1

David Fletcher 2021-5-7

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/824630-how-can-i-display-prime-numbers-with-their-number-of-order#answer_694760

在 MATLAB Online 中打开

A simple solution would be to just add a counter variable:

limit = input('Prime numbers up to :  ');
    if limit == 1
        disp('Please enter a number greater than 2!')
    end
    
    order=1;
    for n = 2:limit
        identDivisor = logical(false);
        k = 2;
        while k < floor(sqrt(n))+1 && identDivisor == false
            if mod(n,k) == 0
                identDivisor = true;
            end
            k = k + 1;
        end
        if identDivisor == false
            fprintf('%d. %d\n',order,n)
            order=order+1;
        end
    end
    return