How size command do as built in command?

I want to know how size works as a built in command in matlab. On the other hand, I want to know how the size command discerns the end of the data in array.

Answer 1

[Image Analyst]

This (Steve's blog) may help: http://blogs.mathworks.com/steve/2011/03/22/too-much-information-about-the-size-function/