Items tagged with nonlinear nonlinear Tagged Items Feed

Hello,

I'm trying to fit a double-diode equation using Maple.  I can get an analytic form of the fitting function in my two variables V and J of the form V(J), but I want J(V), so I'm using fsolve to extract this.  I'm then trying to fit the resulting function to a set of experimental data, but I'm getting an error about writing to an rtable.  I've tested the function, and it gives me a numeric value if I give it numeric inputs.  Is there a way I can fit it?  Code is below:

Hallo,
I have to estimate a logistic growth function, with the functional form
f(t)=A/(B+exp(-k*t))
The dataset is given by

X:=[1950,1960,1970,1980,1990,2000,2010];

which describes the values of t
and by

Y:=[2.53,2.76,3.12,3.75,4.2,4.3,4.35];

which describes the values of f(t).
I now have to estimate the values of A,B and k.
I tried NonlinearFit by

with(Statistics):
NonlinearFit(A/(B+exp(-k*t)),X,Y,t);

I've written 2 long nonlinear symbolic equations with 2 unknowns in Maple, but it doesn't solve it and says:"Kernel connection has been lost".

I have attached my worksheet to this message; what should I do?

problem.mw

I want to solve numerically the nonlinear problem 

a*(diff(y(x), x, x))+2*(diff(y(x), x))+exp(y(x)) = 0, y(0) = 0, y(1) = 0

by defining my own method defined as 

y_n+1=y_n+2*h*(-2*y_n+2*ln(2/(1+x))-(1/2)*a)^2/(a*(-4*y_n+4*ln(2/(1+x))-a-h*(4*y_n-4*ln(2/(1+x))+a+x+1)/a))

where h is the step-size. Please help me by letting me know how can I do this using Maple 11.

Hi all,

I try to solve the following nonlinear programming problem:

but this error message appear:

I am aware of how to plot the feasible region defined by a system of linear inequalities (inequal in the plots package). Also, I can use the implicitplot command to plot the feasible region defined by a single nonlinear inequality. My question is, how do I plot the feasible region defined by a system of nonlinear inequalities. For example, how would a graph the region satisfying x>=0, y<=exp(-x), and y>=x^2?

Hello everyone, I am new on Maple, I am trying to solve a system of six nonlinear algebraic euqation..and can't get it to work..if someone can help me.. model2.mw

I'm trying to approximate points with a function of certain form with Statistics[NonlinearFit]. I expect the graph in the second example to be closely approximate of the points, just like the first graph. For some reason, the second graph is way off. Seems like a bug. Any suggestions are highly appreciated.

Here is the code

plotApprox := proc(listName)
    local X, Y, convModel, modList;

Can Maple 13 solve nonlinear algebraic equations system numerically without using fsolve? for example Gauss siedel iterative method .

Greetings All

I have several equations and each have their own individual frequencies and amplitudes. I would like to sum the equations together and adjust ONLY the individual phases, phase1,phase2, and phase3 to keep the total amplitude value of eq_total under a specific value like 0.8. I know I can normalize the signal or change the vertical offset, but for my purposes I need to have the amplitude controlled by changing/finding the values for just...

Hello everyone.

Now, I am studying nonlinear fitting method through help file of maple. Unfortunately, I'm not getting good fit using NonliearFit. The following is my psocedure:

> restart;
> with(Statistics);
> y := 1/(3.6+2.3*x)+17.6*exp(-0.2*x);
> fy := unapply(y, x);
> for x to 10 do fy(x) end do;
14.5791527795
11.9195840297
9.75432289049
7.98631476846
6.54090333018
5.35848939402
4.39086798669

Hello everyone

I have a function, constructed by numerically solving a set of differential equations.  I need to find a best fit for this function with an analitic model with two parameters. I tried to extract some points of this function and then using nonlinearfit:

xvalues:=Vector([seq(10⁵ ..10⁶,10⁴);

yvalues:=Vector([seq(evalf(function),x=10⁵ ..10⁶,10⁴)]);

with(Statistics):

Does anyone know a command for using Newton's method to a solve a nonlinear system, particularly this one:

4y^2+4y+52x=19

169x^2+3y^2+111x-10y=10

?

Also, how about this one:

x+e^-1x+y^3=0

x^2+2xy-y^2+tan(x)=0

?

Thank you

Hi,

A while back, I was trying to use Maple's NonlinearFit function, but I kept getting an error regarding the input.  Any help you might be able to give me would be appreciated.  Thanks much.

And so with this provocative title, "pushing dsolve to its limits" I want to share some difficulties I've been having in doing just that. I'm looking at a dynamic system of 3 ODEs. The system has a continuum of stationary points along a line. For each point on the line, there exist a stable (center) manifold, also a line, such that the point may be approached from both directions. However, simulating the converging trajectory has proven difficult.

I have simulated as...