Re: Fuction definition
- To: mathgroup at smc.vnet.net
- Subject: [mg73672] Re: [mg73635] Fuction definition
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Sat, 24 Feb 2007 02:18:46 -0500 (EST)
- Organization: Mathematics & Statistics, Univ. of Mass./Amherst
- References: <200702230942.EAA17911@smc.vnet.net>
- Reply-to: murray at math.umass.edu
If you study the documentation about =: (SetDelayed) you will see that the expression on its right in p Sin[Pi x], for example, is evaluated not when you make the definition but rather when you subsequently evaluate an expression involving the left-hand side f2[x]. In your example, you don't ask for f1[0.5] until AFTER you have evaluated p = 2 (where = is Set). Unless and until you change the value of p, it will keep the value of 2, and so evaluating f1[0.5] is the same thing as evaluating 2 Sin[Pi 2]. bar at ANTYSPAM.ap.krakow.pl.math.umass.edu wrote: > Hi > > When I try : > ------------------ > p = 1; > f1[x_] := p Sin[Pi x]; > p = 2; > f2[x_] := p Sin[Pi x]; > > f1[0.5] > f2[0.5] > > Out[26]=2. > > Out[27]=2. > ----------------- > When I use = instead of := it works OK. > Why ? > > It is safely to use "=" in function definition ? > > I have to integrate and differentiate such function in the future. > In my case function depends on about 20 parameters, which are calculated > three times, (I want to obtain three functions) > > I'm not sure is this good idea to use '=' ? > > Regards , Olaf > > > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305
- References:
- Fuction definition
- From: bar@ANTYSPAM.ap.krakow.pl
- Fuction definition