Changing prime numbers in a matrix
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I printed a 100x100 random matrix of integers from 1 to 50. However, I want to replace the prime numbers in this matrix with the number 1415. How can I replace the prime numbers in that matrix with a specific number (1415)? Thank you.
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Scott MacKenzie
on 16 Jun 2021
M = randi([1 50],100);
M(isprime(M)) = 1415;
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Scott MacKenzie
on 16 Jun 2021
Ok, sure. This modification stores the locations of the prime numbers in a logical variable, outputs the prime numbers, then replaces the prime numbers in M with 1415.
M = randi([1 50],100);
% find locations in M containing prime number
primeLogical = isprime(M);
% output prime numbers in M
M(primeLogical)
% change prime numbers in M to 1415
M(primeLogical) = 1415;
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