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MathGroup Archive 1996

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Re: Rule to Function, Frontend funnies

  • To: mathgroup at smc.vnet.net
  • Subject: [mg5320] Re: Rule to Function, Frontend funnies
  • From: haberndt at dnai.com (Harald Berndt)
  • Date: Wed, 27 Nov 1996 01:47:37 -0500
  • Organization: DNAI ( Direct Network Access )
  • Sender: owner-wri-mathgroup at wolfram.com

In article <57645l$28t at dragonfly.wolfram.com>, Wouter Meeussen
<meeussen.vdmcc at vandemoortele.be> wrote:

> how can I convert a rule to a function?
> if I get a result from 
> 
> rulesoln = DSolve[{y'[x]==y[x]/(c+1/x),y[0]==1},y[x],x]
> 
> in the form :
> 
>                                2
>            x/c - Log[1 + c x]/c
> {{y[x] -> E                     }}
> 
> how do I get the definition :
> 
> y[x_]:= E^(x/c - Log[1 + c x]/c^2)
> 


Simply change the attribute of the output cell
from Formatted to Not Formatted. On the Mac that is <Command>+t, on
Windows it's something similar (<Alt>+t or <Ctrl>+t). Then copy and paste,
but even easier ...



> Flatten[rulesoln]/.y[x]->y[x_]/.Rule->SetDelayed
> 
> {Null}


... simply write

   In[5]:=
      y[x_] := Evaluate[y[x]/.Flatten[rulesoln]]

That still leaves undefined parameter c, so you might consider

   In[5]:=
      y[x_][c_] := Evaluate[y[x]/.Flatten[rulesoln]]

Best,

-- 
Harald Berndt, Ph.D.                            Research Specialist,
Voice: 510-652-5974                                      Consultant
FAX:   510-215-4299


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