Re: Procedure to Function
- To: mathgroup at smc.vnet.net
- Subject: [mg8180] Re: Procedure to Function
- From: Paul Abbott <paul at physics.uwa.edu.au>
- Date: Mon, 18 Aug 1997 03:07:04 -0400
- Organization: University of Western Australia
- Sender: owner-wri-mathgroup at wolfram.com
Robert Pratt wrote:
> I am having difficulty rewriting a short procedure as a single function.
> Can anyone explain why I get the wrong answer using the function instead
> of the procedure? Given a harmonic function u[x,y], I'm trying to find
> its harmonic conjugate v[x,y] (so that the Cauchy-Riemann equations hold).
>
> PROCEDURE
>
> Clear[u, v, x, y, g]
> u = x^3 - 3 x y^2 + y;
> v[x_, y_] := Integrate[D[u,x],y] + g[x];
> g[x_] := Evaluate[g[x] /.DSolve[D[v[x, y],x] == D[u,y], g[x], x][[1]]];
> v[x, y]
>
> -x + 3 x^2 y - y^3 + C[1]
How about the following?
In[1]:= HarmonicConjugate[u_, x_, y_] := Module[{v,g},
v = Integrate[D[u,x], y]+g[x];
v /. First[DSolve[D[v, x] == D[u, y], g[x], x]]]
In[2]:= HarmonicConjugate[x^3 - 3 x y^2 + y, x, y]
Out[2]= -y^3 - 3 x^2 y + x + C[1]
This way v and g are local to the Module and u, x, and y are passed as
input.
Cheers,
Paul
____________________________________________________________________
Paul Abbott Phone: +61-8-9380-2734
Department of Physics Fax: +61-8-9380-1014
The University of Western Australia
Nedlands WA 6907 mailto:paul at physics.uwa.edu.au
AUSTRALIA http://www.pd.uwa.edu.au/Paul
God IS a weakly left-handed dice player
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