Split symbolic function by terms

In general i have a function that looks like

f = f1 + f2 + f3 +...+fn

and i want to address/modify/evaluate only f1 or f2 or f3. For example

   f = 1/(x*y-1) + (x+2)/(y^2*(x-1)) + 1/(x^2*y^3-1)

and i want to get only 1/(x*y-) or one of the other two.

Answer 1

[Walter Roberson]

http://www.mathworks.com/help/symbolic/children.html at the MATLAB level

http://www.mathworks.com/help/symbolic/mupad_ref/op.html at the MuPAD level

[Skye]

ty, exactly what i was looking for

[Yu-Chun]

https://www.mathworks.com/help/symbolic/sym.children.html

Edit (by Dyuman Joshi)

The link mentioned in the answer no longer directs to the intended resource.

This is the updated link for the documentation page of the function children

[Walter Roberson]

Right, this is the updated URL for the children that I mentioned a number of years ago.

[Dyuman Joshi]

Yes, this has been provided in the answer above, ~9 years ago.

Why repeat it, after such a long time?

[Walter Roberson]

The url for children() changed so it is valid to post the updated url