Chapter 4: Programming in Matlab - College of the Redwoods

Section 4.1 Logical Arrays 281
>> u=[2,3], v=[4 5 6], u|v
u =
2 3
v =
4 5 6
??? Error using ==> or
Inputs must have the same size.
Let’s look at some powerful applications of these operators.
◮ Example 3.
Find all entries of matrix magic(5) that are not prime.
Start by entering the matrix and using Matlab’s isprime function to find the
prime entries.
>> M=magic(5); B=isprime(M);
We saw in an earlier example that M(B) will list all of the primes in the matrix
M. So, let’s use the logical operator ~ to list all the nonprimes. For convenience
and purposes of comparison, we list the matrix M.
>> M
M =
17 24 1 8 15
23 5 7 14 16
4 6 13 20 22
10 12 19 21 3
11 18 25 2 9
Now we list all the nonprimes in the matrix M.