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MathGroup Archive 1996

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Rule to Function, Frontend funnies

  • To: mathgroup at smc.vnet.net
  • Subject: [mg5307] Rule to Function, Frontend funnies
  • From: Wouter Meeussen <meeussen.vdmcc at vandemoortele.be>
  • Date: Sat, 23 Nov 1996 01:44:44 -0500
  • Sender: owner-wri-mathgroup at wolfram.com

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)

(*************************************************************************)
Funny  : in any text editor, like notepad , I just cut & paste the pieces I
need.
In the Frontend, I can force Mma to produce a one-dimensional output line by
asking
 % // InputForm

{{y[x] -> E^(x/c - Log[1 + c*x]/c^2)}}

but when I try to edit it, or make an input-line out of that, either by
Action-Prepare.Input-Copy.Output.from.Above (Control-Shift-L)
or by Menu-Cell-Inactive and Menu-Style-Input, the result is :

No Input Form was generated for this Cell

(*************************************************************************)
Even Funnier : doing Control-Shift-L and Shift-Enter produces:
 
General::spell: Possible spelling error: new symbol name "Form"
     is similar to existing symbols {CForm, For}.
General::spell1: Possible spelling error: new symbol name "for"
     is similar to existing symbol "For".

Cell for Form generated Input No this was
(*************************************************************************)


Anybody out there to whom this happens too? 
After some {soul,FullForm}-searching, I came up with this rule-eating-rule :

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

{Null}

you don't get to see much except "{Null}", but it results in:

?y

Global`y
y[x_] := E^(x/c - Log[1 + c*x]/c^2)

(*************************************************************************)

Is there a fast & easy Cut-and-Paste way to do it, not leaving the FrontEnd?
Is this the same on a Mac-machine?
Is this the same in Mma 3.0 for Windows?


Wouter.

NV Vandemoortele Coordination Center
Group R&D Center
Prins Albertlaan 79
Postbus 40
B-8870 Izegem
Tel: +/32/51/33 21 11
Fax:+32/51/33 21 75
vdmcc at vandemoortele.be



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