Re: How to define a polyfunction?

*To*: mathgroup at smc.vnet.net*Subject*: [mg27422] Re: [mg27389] How to define a polyfunction?*From*: Tomas Garza <tgarza01 at prodigy.net.mx>*Date*: Sun, 25 Feb 2001 00:53:49 -0500 (EST)*References*: <200102230733.CAA06963@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Regardless of the term "polyfunction", In[1]:= golf[t_] := t^2 - t; In[2]:= key[t_] := If[(golf'[x] /. x -> t) > 0, (t^4 + t*3), (t^2.5 - t)]; In[3]:= key[2] Out[3]= 22 In[4]:= key[0.4] Out[4]= -0.298807 This will show the discontinuity at t = 0.5 induced by the definition: In[5]:= Plot[key[t], {t, 0, 1}] Tomas Garza Mexico City ----- Original Message ----- From: "liwen liwen" <gzgear at yahoo.com> To: mathgroup at smc.vnet.net Subject: [mg27422] [mg27389] How to define a polyfunction? > Dear friend, > How are you!Now I encounter a problem that I > can not solve for a long time . > It can be express simplely as how to define a > polyfunction,for example,a simple polyfunction may be > defined as that: > > Key[t_]:=If[(t>0),1,0]; > > It is easy to define.However,it will be more difficult > when the condition turns more complicate.For instance: > golf=t^2-t; > Key[t_]:=If[(D[golf[t],t]>0),(t^4+t*3),(t^2.5-t)]; > > > Best regards, > > > Liwen > E-mail: gzgear at yahoo.com > > __________________________________________________ > Do You Yahoo!? > Yahoo! Auctions - Buy the things you want at great prices! http://auctions.yahoo.com/ >