How to convert flowchart to MATLAB code ?

Question

sony 2023-11-6

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2043352-how-to-convert-flowchart-to-matlab-code

回答： DGM 2023-11-16

prime number flowcharts.pdf

Dear Sirs, please help me to convert this flowchart to MATLAB code.

I am facing some difficulties in loops I tried hard to solve it several times but I couldn't.

it is about inputting a number and printing out if it prime number or not.

I would appreciate it if you could help me with this.

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sony 2023-11-7

在 MATLAB Online 中打开

counter = 2;
num = 0;
i = mod(num, counter);
disp('Enter Number');
num = input('');
while (num <= 0)
    disp('Enter Number');
    num = input('');
end
if (mod(num, 2) == 0)
    disp('not prime number');
end
if (mod(num, counter) > 0)
    counter = counter + 1;
    if (i == 0)
        disp('prime number');
    end
end

I tried this but I am stuck in the second loop on how to do it.

before this, I tried 20 times or more.

sorry, I am a beginner.

thanks, a lot.

sony 2023-11-7

在 MATLAB Online 中打开

% Prompt the user to enter a positive integer
n = input('Enter a positive integer: ');
% Initialize the flag variable
is_prime = true;
% Check if the entered number is 0 or 1
if (n == 0 || n == 1)
    is_prime = false;
end
% Check if the entered number is divisible by any number from 2 to n/2
for i = 2:n/2
    if (mod(n, i) == 0)
        is_prime = false;
        break;
    end
end
% Display the result
if (is_prime)
    disp([num2str(n), ' is a prime number']);
else
    disp([num2str(n), ' is not a prime number']);
end

I found this solution it be good and makes sense but I am wondering how to do it like the previous flowchart.

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Answer 1

Walter Roberson 2023-11-6

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https://ww2.mathworks.cn/matlabcentral/answers/2043352-how-to-convert-flowchart-to-matlab-code#answer_1347597

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sony 2023-11-7

Thanks a lot, it is really tools help.

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Answer 2

DGM 2023-11-16

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2043352-how-to-convert-flowchart-to-matlab-code#answer_1353837

在 MATLAB Online 中打开

This is what I was squatting on. It's not a literal interpretation of the flowchart, but there's no good reason to use a literal interpretation.

% don't harrass the user for inputs 
% unless you like collecting typos
N = 456156445111;
% use a flag instead of a scattered bunch of redundant disp() calls
% avoid entering the loop if at all possible
P = [2 3 5 7 11 13 17 19 23 29 31 37]; % known small primes (as many as you want)
if ismember(N,[1 P]) % is N a known small prime?
    nisprime = true;
elseif any(~mod(N,P)) % does N have known small prime factors?
    nisprime = false;
else % this is slow
    for C = 2:N-1
        if ~mod(N,C)
            nisprime = false;
            break;
        end
    end
    nisprime = true;
end
if nisprime
    disp('prime')
else
    disp('not prime')
end