Problem with Separable Differential eq.
- To: mathgroup at smc.vnet.net
- Subject: [mg17679] Problem with Separable Differential eq.
- From: Chatzikonstantinou Ioannis <jhatziko at math.auth.gr>
- Date: Fri, 21 May 1999 23:58:58 -0400
- Organization: Central Computing Facility, Aristotle University of Thessaloniki
- Sender: owner-wri-mathgroup at wolfram.com
Hello Mathematica users,
I have stuck in the following problem and I would be truly obliged
to anyone who can help
Thank you in advance!!
Separable Differential Equation (with 2 general solutions at most)
P1: polynomial of x
P2: polynomial of y
X: Variable
Y: Variable
I_List: Interval of C constant (in general solution y) for making plot
T_list: Initial Values to find C {x,y[x]}
My problems with this programme are:
1) The constant C. I want to know if there is a way to put the constant
C in w=Solve[a==b+c]
without seeing this constant ,when I run the programme, in the form C$
2) In the initial value problem when I have two solutions for y (one
positive and one negative). I want to take one of them according to sign
of the second value in t_List. Then I want to replace the known value of
C in solution y and make the ImplicitPlot.
<<Graphics`ImplicitPlot`
g[p1_,p2_,x_,y_,i_List,t_List]:=
Module[{ a,b,w,c,r,q,toplot,gensole,sol,cval,de,j},
a=Integrate[p1,x]//Simplify;
b=Integrate[p2,y]//Simplify;
w=Solve[a==b+c,y]//Simplify;e=y/.w;j=e[[1]];
d=Print["THE GENERAL SOLUTION IS:"w];
If[t=={},toplot=Table[j[[m]]/.c->r,{r,i[[1]],Max[i],0.5},{m,1,Length[j]}];
q=Short[toplot];Plot[Evaluate[toplot],{x,0.5,Max[i]},
PlotRange->{{0,Max[i]},{0,Max[i]}},AxesStyle->GrayLevel[0.6],
AspectRatio->1],
gensole=a==b+c;cval=Solve[gensole/.{x->t[[1]],y->t[[2]]},c];
sol=gensole/.(cval[[1]]);
ImplicitPlot[sol,{x,-3,3},{y,-3,3},AxesOrigin->{0,0},
AxesStyle->GrayLevel[0.5]]];w]
--
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Chatzikonstantinou Ioannis
Karakasi 27 str. 54248, Thessaloniki
GREECE
mailto:jhatziko at math.auth.gr
tel : ++30-31-865297
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