How do I test for integers in MATLAB?

Question

I\'m writing a program that will calculate factorials of integers. However, the part I\'m stuck on is if someone enters a non-integer such as 1.3, I\'d like to

Answer 1

You can cast the value to an integer and back to a double and check the result against the original value:

>> x = 1.3;
>> x == double(uint64(x))

ans =

     0

>> x = 2;
>> x == double(uint64(x))

ans =

     1

Interestingly, R.M.'s approach of using MOD runs faster in a loop and the above casting approach runs faster when vectorized:

>> x = rand(100000, 1);
>> tic; for ii = 1:100000; ~mod(x(ii), 1); end; toc;
Elapsed time is 0.018380 seconds.
>> tic; for ii = 1:100000; x(ii) == double(uint64(x(ii))); end; toc;
Elapsed time is 0.383020 seconds.
>> tic; ~mod(x, 1); toc;
Elapsed time is 0.005299 seconds.
>> tic; x == double(uint64(x)); toc;
Elapsed time is 0.002971 seconds.