What does a(a<0) = 0 mean in matlab?

I am new to matlab.

What does a(a<0) = 0 mean?

is it valid if a is an array as well?

Answer 1

[Cris LaPierre]

Yes, it works on arrays. It is using logical indexing to assign values to a. You can learn more about logical indexing in Ch 11 of MATLAB Onramp.

Basically, set any value in a that is less than zero to zero. Here's a simple example.

a = rand(3)

a = 3×3

0.0787 0.4977 0.0631 0.2203 0.4529 0.4654 0.9312 0.7561 0.7632

a<0.5

ans = 3×3 logical array
   1   1   1
   1   1   1
   0   0   0

a(a<0.5)=0

a = 3×3

0 0 0 0 0 0 0.9312 0.7561 0.7632

Answer 2

[Adam Danz]

> What does a(a<0) = 0 mean?

a can be a scalar or an array.

This replaces all values in a that are less than 0 with 0.

Example

a = [-6: 2 : 6]

a = 1×7

-6 -4 -2 0 2 4 6

a(a<0) = 0 

a = 1×7

0 0 0 0 2 4 6