Counting number of elements less than value across 2d matrix

I have a two-dimensional matrix of numbers size A(720,1440). I'd like to calculate the percent of values in part of the matrix -- i.e., from 401:440 and 1081:1360 -- where values are less than or equal to 5, exclusing NaN values.

In order to accomplish this, I'd like to first count the number of elements for this part of A (401:440,1081:1360) where values are less than 5, but omiting any NaN values.

I'm trying to do this using the sum function like below but I'm striking out. Any suggestions?

sum(A(401:440,1081:1360)<=5)

Answer 1

[Adam Danz]

> I'd like to calculate the percent of values in part of the matrix -- i.e., from 401:440 and 1081:1360 -- where values are less than or equal to 5, exclusing NaN values.

A = randi(10,720,1440); 
mu = mean(A(401:440,1081:1360)<=5,'all','omitnan')

mu = 0.4957

> I'd like to first count the number of elements for this part of A (401:440,1081:1360) where values are less than 5, but omiting any NaN values.

As you can see above, this step isn't needed. But for completeness,

count = sum(A(401:440,1081:1360)<=5,'all','omitnan')

count = 5552

To verity the mean computed above,

totalNumberOfElements = numel(A(401:440,1081:1360))

totalNumberOfElements = 11200

myConfirmed = count/totalNumberOfElements

myConfirmed = 0.4957