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Question: checking if an expression is free of x

Question:checking if an expression is free of x

nm 10758
January 09 2015
2

I was trying to see if Maple contains equivalent to Mathematica FreeQ command to check inside a proc if an input expression contains an "x" or not.  I could not find such command in Maple. So now I call indets(), which is a nice function, that tells me all the symbols in the expression, then use member() to check.

Would this be correct way to do this? Here is an example

expr:=3+4*sqrt(2)-x+y*sin(3*t);
s:=indets(expr);
if member(x,s) then
   print(`yes, x is there`);
fi;

I can't use patmatch() for this, as I do not know what the expression will look like yet, I just needed to know if it contains an "x" (in this case), a free symbol "x", and that is all.

I thought to ask if there is a better way to do this.
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