Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Software » comp.soft-sys.matlab

Topic: Counting problem
Replies: 4   Last Post: Feb 7, 2013 3:46 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Jos

Posts: 1,266
Registered: 10/24/08
Re: Counting problem
Posted: Feb 7, 2013 6:43 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

"Erasmus" wrote in message <keuijo$cvu$1@newscl01ah.mathworks.com>...
> hello everyone, I want count how many times of number meet the specific criteria.
> for example, I have two matrix, A and B, I want to count the how many times of element meet two criteria,1) the element in A is less than 1; 2) the corresponding element(in the same location) in B is larger than 50,.
>
> for example
>
> A= [ 0.1 0.2 0.5
> 0.9 1.3 1.2
> 0.7 1.2 1.5]
> B=[2 34 43
> 54 55 56
> 62 43 45]
>
> so meet the times meeting these two criteria is 2 times, location[3,1] and [2,1]
>
> Does anyone can help me? thank you very much!


Create logical matrices using your criteria, like
tfA = A < 1
tfB = B > 50
tfAB = tfA & tfB
N = sum(tfAB(:))

The colon is needed to sum over all elements. All this can be combined in a single line, which is, however, more difficult to understand.

N = sum(A(:)< 1 & B(:)>50)

~ Jos



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.