Re: How to Enable Automatic Recalculation
- To: mathgroup at smc.vnet.net
- Subject: [mg109866] Re: How to Enable Automatic Recalculation
- From: Victor Roberts <xxx at lighting-research.com>
- Date: Thu, 20 May 2010 06:39:14 -0400 (EDT)
- References: <ht1uua$3cf$1@smc.vnet.net>
Thanks Murray. Dynamic is very close to what I was looking for. -- Vic Roberts Replace xxx with vdr in e-mail address. On Thu, 20 May 2010 00:15:06 +0000 (UTC), Murray Eisenberg <murray at math.umass.edu> wrote: >There IS a "simple" answer. Actually, two answers. it used to be that >the only way to do this was to use SetDelayed ( := ) for the symbol you >wanted to be recalculated whenever you changed another variable whose >values was specified by Set ( = ). Since Mathematica 6, you also have >the more sophisticated method of using Dynamic quantities. > > (* method 1: use SetDelayed instead of Set for b *) > a = 5; > b := 3 + a > b >8 > a = Pi; > b >3 + Pi > > > (* method 2: use Dynamic *) > Clear[a,b] > Dynamic[a] >a > a = 3; (* preceding output changes to 3 *) > b = 3 + a >6 > a = Pi; > b >3 + Pi > > (* method 3: another way to use Dynamic *) > Clear[a,b] > a = 3; > Dynamic[b = 3 + a] >6 > a = Pi; (* preceding ouptput changes to 3 + Pi *) > b >3 + Pi > > > >On 5/19/2010 7:01 AM, Victor Roberts wrote: >> I'm new to Mathematica, so perhaps there is a simple answer >> to this question. >> >> How to I set Mathematica so that when I change the value >> assigned to a variable it will automatically change all >> later calculations that use that variable. >> >> For example, if I set >> >> a = 5 >> >> and >> >> b = 3 + a >> >> I would like the value of b updated each time I change the >> value of a. >> >> Right how, I need to recalculate each and every expression >> that uses the variable a if I change its value. There must >> be a better way. >> >> >> -- >> Vic Roberts >> Replace xxx with vdr in e-mail address. >>