My professor assigned me to do the this homework with two numbers and writing a code that find which one is the prime for these two numbers

Write a user-defined function that determines if a number is a prime number. Name the function pr=Trueprime(m), where the input arguments m is a positive integer and the output argument pr is 1 if m is a prime number and 0 if m is not a prime number. Do not use MATLAB’s built-in functions primes and isprime. If a negative number or a number that is not an integer is entered when the function is called, the error message “The input argument must be a positive integer.” is displayed.

(a) Use the function with 733, 2001, and 107.5

%%This is for one number
function pr=Trueprime(m)
if floor(m)~=m
    disp('number is not a whole number')

else
 for i=2:1:(m-1)
     if rem(m,i)==0
         disp('Number is not prime')
         break
     end
     if i==(m-1)
         disp('Number is prime')
     end
 end
end

Answer 1

[David Fletcher]

So what is the problem? The only obvious issue I see is that it doesn't check if the number is negative:

function pr=Trueprime(m) 

if floor(m)~=m | m<=0
    disp('The input must be a positive integer')
else
    for i=2:1:(m-1) 
        if rem(m,i)==0 
            disp('Number is not prime') 
            break 
        end
        if i==(m-1) 
            disp('Number is prime') 
        end
    end
end

[Nezar Ayoub]

My question was if i have two numbers for example Trueprime([733 2001]). I am changing the question to two numbers instead of one number as in the question giving in the book part a, b and c Trueprime(733) Trueprime(2001) Trueprime(107.5)

[David Fletcher]

Probably a few ways you can go about it, but you've already written a function for single number prime, so make that a local function to a generalized Trueprime function that takes a vector argument like:

 function pr=Trueprime(m) 

result=zeros(1,length(m));

if any(floor(m)~=m) | any(m<0)
    disp('The input must be a positive integer');
    result=-1;
else
    for iter=1:length(m)
        result(iter)=privatePrime(m(iter));
    end
end

pr=result;

end

function res=privatePrime(m)
pr=1

for i=2:1:(m-1)
    if rem(m,i)==0
        pr=0;
        break
    end

end

res=pr;

end

Trueprime([107 20 5 200 11])

ans =

       1     0     1     0     1