Thread Subject:

Counting problem

I have a square matrix Z and need to count the number of elements within it that are a) smaller than 0.5, or b) greater than 179.5, and c) do not lie on the diagonal.

How would you recommend doing this? length(find(Z<0.5)) + length(find(Z>179.5) does the first two conditions, but how the third?

With thanks,
Sepehr

"Sepehr Sadighpour" <sepehr125@gmail.com> wrote in message <i4jigq$9av$1@fred.mathworks.com>...
> I have a square matrix Z and need to count the number of elements within it that are a) smaller than 0.5, or b) greater than 179.5, and c) do not lie on the diagonal.
>
> How would you recommend doing this? length(find(Z<0.5)) + length(find(Z>179.5) does the first two conditions, but how the third?
>
> With thanks,
> Sepehr

You could also do this:
sum(Z(:)<0.5)

One way:

New_Z = Z(~eye(length(Z)));
%Math on New_Z
 

"Sepehr Sadighpour" <sepehr125@gmail.com> wrote in message <i4jigq$9av$1@fred.mathworks.com>...
> I have a square matrix Z and need to count the number of elements within it that are a) smaller than 0.5, or b) greater than 179.5, and c) do not lie on the diagonal.
>
> How would you recommend doing this? length(find(Z<0.5)) + length(find(Z>179.5) does the first two conditions, but how the third?
>
> With thanks,
> Sepehr
- - - - - - -
count = nnz((Z<0.5|Z>179.5)&~eye(size(Z)));

Roger Stafford

And another:
S = Z<.5 | Z>179.5;
count = sum(S(:)) - sum(diag(S))