Return the number of rows of an array

Hi, I just started using Matlab and is confused on how to extract the row indices/ row numbers.

For example, I have a function A:

A = [10 20 30 40 50 60 70 80 90 100]

I wanted to extract the row which has elements less than 50 so it will give

B= [1 2 3 4] (from row 1 to 4)

May I know how to do this? Any help and advice is greatly appreciated

[Stephen]

You seem to have confused rows with columns:

Your example A has only one row and ten columns, whereas your example B has one row and five columns.

Answer 1

[Stephan]

A = [10 20 30 40 50 60 70 80 90 100] 

A = 1×10

10 20 30 40 50 60 70 80 90 100

B = A(A<50)

B = 1×4

10 20 30 40

[Riley]

Hi Stephan, thanks for answering. But I'm trying to return the row instead of the element inside the matrix. May I know how to do this?

[Stephan]

A = [10 20 30 40 50 60 70 80 90 100] 

A = 1×10

10 20 30 40 50 60 70 80 90 100

[row, col] = find(A<50)

row = 1×4

1 1 1 1

col = 1×4

1 2 3 4

[Riley]

Thanks, Stephen!

Answer 2

[Alex Alex]

B=find(A<50)

[Stephen]

Note that strictly this returns the linear indices, not row (or column) subscript indices.

[Riley]

Thanks, Alex