2.4 | 9 ratings Rate this file 45 downloads (last 30 days) File Size: 253 Bytes File ID: #2006

isodd

18 Jul 2002 (Updated 19 Jul 2002)

No BSD License

Checks to see if a number is odd or even.

File Information
Description	Determines if a number is odd or even by dividing the number by two an seeing if the number is an integer.
MATLAB release	MATLAB 6.1 (R12.1)

Tags for This File
Everyone's Tags	even, logic, mathematics, odd, parity
Tags I've Applied
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Comments and Ratings (12)
22 Jul 2002	anonymous anonymous	This is a lot of code, this should just be one line: x = mod(number,2)~=0; This is vectorized, and works for negatives, too. If you want the test to fail for negatives, then use: x = mod(number,2)>0;
24 Jul 2002	The Author	Well had I known that, I could have used that. But this is an old function, and a fairly simplistic method that works. However, I have now adpoted the above method as it does allow you to use vetors.
02 Dec 2002	Rasmus Anthin	Myself I use "~~mod(x,2)" all the time nowadays (then "~mod(x,2)" as "iseven()" of course). If you wan't to go fast then I think your way is better. Unfortunately your routine only works for scalars. Instead try: ~~(x/2-floor(x/2)) which is vectorized and FAST (since "floor" is inbuilt. Type "type mod" and you'll see why). This is about 5 times faster than ~~mod(x,2).
17 Jan 2004	Lewis Camill	good...
09 Jun 2005	Camilo Cano	Great and simple. Thanks.
05 Dec 2005	Duane Hanselman	Works only for scalar inputs when it could easily work for an array of any dimension. Problem made much more difficult than needed. Rasmus review provides a simple one-liner.
25 Jan 2006	Mohammed Serhir	to complicated for simple function
20 Sep 2006	John Dough	should there be an "a whole" joke here?
08 Dec 2006	Johan Tolosa	What is Rasmus review's one liner? Can you post it here please? Thanks.
12 Dec 2006	Matlab Noob	alternatively, one could use isodd=inline('x-2*floor(x/2)','x');
02 Mar 2008	D St	The function would be more efficient if it avoided calculating the "part" variable, avoided using an "if", and just did its job by "x = (a != whole)"
19 Mar 2008	aanon aanon	even easier, whole thing rem(number/2) true if odd, false if even.

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Tag Activity for this File
Tag	Applied By	Date/Time
parity	Richard Medlock	22 Oct 2008 06:46:43
odd	Richard Medlock	22 Oct 2008 06:46:43
even	Richard Medlock	22 Oct 2008 06:46:43
logic	Richard Medlock	22 Oct 2008 06:46:43
mathematics	Richard Medlock	22 Oct 2008 06:46:43

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