Re: Assigning (really dumb question)

*To*: mathgroup at smc.vnet.net*Subject*: [mg60993] Re: Assigning (really dumb question)*From*: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>*Date*: Fri, 7 Oct 2005 03:37:39 -0400 (EDT)*Organization*: Uni Leipzig*References*: <di2ml8$8h0$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, Solve already return a list of replacement rules and r[q] /. qa instead of r[q] /. q->qa should work. Regards Jens <vjp2.at at at.BioStrategist.dot.dot.com> schrieb im Newsbeitrag news:di2ml8$8h0$1 at smc.vnet.net... | What the heck am I doing wrong? I've been away from Mathematica for a while. | | I can't get it to evaluate the expressions at the solved values. | | I feel so stupid. | | r[q_] := 1800 q - .006 q^2 | c[q_] := 12100000 + 800 q + .004 q ^2 | | qa = Solve[ D[ r[q]-c[q] , q] == 0, q] | r[q] /. q -> qa | c[q] /. q -> qa | r[q]-c[q] /. q -> qa | D[r[q],q] /. q -> qa | D[c[q],q] /. q -> qa | | qm = Solve[ c[q]/q - D[c[q] , q] == 0, q] [[2]] | r[qm] /. q -> qm | c[qm] /. q -> qm | r[qm]-c[qm] /. q -> qm | D[r[q],q] /. q -> qm | D[c[q],q] /. q -> qm | | | (PS, a while back I was asking how to fix DOS 2.2.2 when it wasn't | doing graphics and I was told it was no longer supported. Well, 2yrs | later, dumbo me, realised I just had to cd into the math directory and | all was fine.) | | | - = - | Vasos-Peter John Panagiotopoulos II, Columbia'81+, Bio$trategist | BachMozart ReaganQuayle EvrytanoKastorian | http://ourworld.compuserve.com/homepages/vjp2/vasos.htm | ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- | [Homeland Security means private firearms not lazy obstructive guards] | [Fooey on GIU,{MS,X}Windows 4 Bimbos] [Cigar smoke belongs in veg food group] |