interpret a simple matrix code

I m interpret a very easy code...

I don't know some points, could you explain green sentences?

>> A=eye(4,4)
A =

Diagonal Matrix

   1   0   0   0
   0   1   0   0
   0   0   1   0
   0   0   0   1

>> for x=(1:2:3) %what is this mean x=(1:2:3) 
A(x,x)=x+1; % first x is line and second x is row right? hence it means (1,1), (2,2), (3,3),(4,4)
end
>> A
A =

Diagonal Matrix

   2   0   0   0
   0   1   0   0
   0   0   4   0
   0   0   0   1

Answer 1

[Jan]

I recommend to use the free Matlab tutorials to learn the basics: https://www.mathworks.com/learn/tutorials/matlab-onramp.html

Read the "Getting Started" chapters of the documentation also.

If you have a question about a for loop, read:

help for
doc for

Here your find what a:b:c means: "initVal:step:endVal"

"hence it means (1,1), (2,2), (3,3),(4,4)" - almost correct: The loop stops at 3, so (4,4) is not included.

[Ann Lee]

thank you! i'll read that tutorials!