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Re: solving nonlinear equation with mathematica !!
*To*: mathgroup at smc.vnet.net
*Subject*: [mg47155] Re: solving nonlinear equation with mathematica !!
*From*: bobhanlon at aol.com (Bob Hanlon)
*Date*: Sun, 28 Mar 2004 00:07:45 -0500 (EST)
*References*: <c438oj$ekr$1@smc.vnet.net>
*Sender*: owner-wri-mathgroup at wolfram.com
Check your graph; you must have a wrong equation.
Needs["Graphics`ImplicitPlot`"];
Needs["Graphics`Colors`"];
eqns={x^2-y-1==0, 10*x*Exp[-x]-y==0};
FindRoot[eqns,
{x,#[[1]]}, {y,#[[2]]}]& /@
{{-0.1, -1}, {2, 2.5}}
{{x -> -0.09058966837961079, y -> -0.9917935119828722},
{x -> 1.9446329780681595, y -> 2.7815974193902346}}
pts = {x, y} /. %;
ImplicitPlot[eqns,{x,-0.2,2.2},
AspectRatio->1/GoldenRatio,
Frame->True, Axes->False,
PlotStyle -> {Blue, Green},
Epilog-> {AbsolutePointSize[4], Red, Point /@ pts}];
Plot[{x^2-1, 10*x*Exp[-x]}, {x,-0.2,2.2},
Frame->True, Axes->False,
PlotStyle -> {Blue, Green},
Epilog-> {AbsolutePointSize[4], Red, Point /@ pts}];
Bob Hanlon
In article <c438oj$ekr$1 at smc.vnet.net>, m004202002 at yahoo.com (why) wrote:
<< I face root finding problem solving nonlinear equation
I have system nonlinear equation
x^2-y-1 = 0;
10x exp(-x)-y = 0 ;
If you draw the graph you see two intersecting point .
I have found a point [Using FindRoot function ]
In (-0.1,-0.5) the point is (-0.0905897,-0.991794 )---it is OK
But
In (2.0,1.0) the point is (1.94463,2.7816)
But the graph says the x->2.something ,y->1.somthing
I have used same FindRoot function to find the root
in (2.0,1.0 ).
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