Re: Extracting terms from an equation
- To: mathgroup at smc.vnet.net
- Subject: [mg69826] Re: Extracting terms from an equation
- From: albert <awnl at arcor.de>
- Date: Sat, 23 Sep 2006 23:45:40 -0400 (EDT)
- References: <eevubf$hqu$1@smc.vnet.net> <ef2t04$mjc$1@smc.vnet.net>
Hi, > Cases[a + b*x^2 + c*y^2 + d*x*y + e*x^3, _?( !FreeQ[#1, x] & )] > {b*x^2, e*x^3, d*x*y} > > Cases[a + b*x^2 + c*y^2 + d*x*y + e*x^3, _?(MemberQ[#1, x] & )] > {d*x*y} MemberQ by default checks for precense of x in the first level only. What you probably want is: Cases[a + b*x^2 + c*y^2 + d*x*y + e*x^3, _?(MemberQ[#1, x,Infinity] & )] which should always give the same result as the version with FreeQ. Use In[4]:= FullForm[e*x^3] Out[4]//FullForm= Times[e, Power[x, 3]] to understand why x is not a member of e*x^3 , but x^3 is... hth, albert