Function for 'does matrix contain value X?'

Question

Is there a built in MATLAB function to find out if a matrix contains a certain value? (ala PHP\'s in_array())

Answer 1

If you need to check whether the elements of one vector are in another, the best solution is ismember as mentioned in the other answers.

ismember([15 17],primes(20))

However when you are dealing with floating point numbers, or just want to have close matches (+- 1000 is also possible), the best solution I found is the fairly efficient File Exchange Submission: ismemberf

It gives a very practical example:

[tf, loc]=ismember(0.3, 0:0.1:1) % returns false 
[tf, loc]=ismemberf(0.3, 0:0.1:1) % returns true

Though the default tolerance should normally be sufficient, it gives you more flexibility

ismemberf(9.99, 0:10:100) % returns false
ismemberf(9.99, 0:10:100,'tol',0.05) % returns true