Question

Write a function called isPrime.m. This function is used to check whether a given number is a prime number or not. The output shows 1 for prime number and 0 for non-prime number.

Example:

isPrime(5)       return 1

isPrime(10)   return 0

Then write a function called checkPrime.m, to check an arrays to show how many prime numbers in this array.

Example:

checkPrime([1,4,5,6,4,7,9,25])

>> count = checkPrime([1,4,5,6,4,7,9,25])

count =

            3.00

Answer 1

isPrime.m:

function output = isPrime(n)

% assume that n is prime

output = true;

% loop over from 2 to n-1

for i = 2:n-1

    % if n is divisible by i

    if mod(n,i)==0

        output = false;

    end

end

end

checkPrime.m:

function count = checkPrime(arr)

count = 0;

% iterate over array

for i = 1:size(arr,2)

    % if current number is prime

    if isPrime(arr(i))

        count = count + 1;

    end

end

end

Output:

>> count = checkPrime ([1,4,5,6,4,7,9,25]) count 3

.