What's this Mathematica function called?

*Subject*: [mg934] What's this Mathematica function called?*From*: martind at carleton.edu (D<martind at carleton.edu>M)*Date*: Wed, 3 May 1995 00:13:19 -0400*Apparently-to*: mathgroup-send at christensen.cybernetics.net*Organization*: Carleton College -- Northfield, MN

First let me apologize for what I'm pretty certain is a question that I could find if only I searched through the big black book long enough. However, I am unable to find an answer anywhere in the index, so I'll ask it here. What is Mathematica function that determines if one expression depends on another? i.e. if this function were called Depends, it would give output something like this: Depends[x + 3, x] ==> True Depends[y, x] ==> False y := x^2 Depends[y, x] ==> True Depends[f[g[x]], x] ==> True Depends[f[g[y]], x] ==> True Clear[y]; Depends[f[g[y]], x] ==> False I seem to remember running across it at some point, but I'm unable to find it now... Daniel Martin martind at carleton.edu