# Search Results

Results tagged with Search options answers only user 6358
26 results

Questions on the analytic and numerical equation solving functions of Mathematica (Solve, Reduce, NSolve, FindRoot, DSolve, RSolve, etc.).

The root tracker TrackRoot I wrote here can be applied to this problem. First, run TrackRoot from that link. Then: x[ϕ_] := 1/(2 Sqrt) (-2/ϕ + Log[(1 + ϕ)/(1 - ϕ)]); tr = TrackRoot[{x[ϕ] - xva …
answered Aug 11 '16 by Chris K
FindRoot only gives one root, not all of them. To find the other, use a different initial guess: V1 = 1; ListPlot@Table[{n, f /. FindRoot[ V1/4 + (f V1)/4 + 1/(4 (-1 + n) Gamma[1/2 (-1 + n)]^2) n^ …
answered Sep 13 by Chris K
A few problems with your code: Curly braces {} can't be used as parentheses (). You need a space or * between k and x to multiply them, otherwise Mathematica thinks it's a new variable kx. The synta …
answered Oct 25 '18 by Chris K
Adding a non-existent Method->"Foo" as here fixes the problem, as does Method->"EndomorphismMatrix".
answered Dec 31 '18 by Chris K
Since @hesam asked about a command, and to get a better understanding of @DanielLichtblau's approach, I tried to generalize it and package it in a function. Feedback would be appreciated! TrackRoot[ …
answered Jan 23 '16 by Chris K
Substituting your symmetry assumption gives the result you're looking for: Simplify[Solve[{D[gA, ϕA] == 0, D[gB, ϕB] == 0} /. {ϕA -> ϕ, ϕB -> ϕ}, ϕ]] (* {{ϕ -> -(((-2 + α) (-1 + β^2))/(-2 + α + α β)) …
answered Aug 4 by Chris K
I noticed a lot of FindRoot::cvmit errors when you run FindRoots2D. I wrapped a Check around the FindRoot in FindRoots2D that effectively excludes these nonconvergent points (by returning points that …
answered Feb 27 '17 by Chris K
I'd love to see a good answer to this, because it's a common problem I face. My crude improvement on your technique is to use the previous parameter value's answer as an initial guess, which helps Fi …
answered Jan 22 '16 by Chris K
As we figured out in the comments section above, adding PlotPoints->100 as an option to FindRoots2D fixes the problem. pts = FindRoots2D[{Ωx, Ωy}, {x, -5, 5}, {y, -5, 5}, PlotPoints -> 100] ContourPl …
answered Aug 1 '16 by Chris K
Here's an approach using some functions for tracking roots I hacked together previously. First, load the function TrackRootPAL defined here. Then, define your functions: f[x_, y_, c_] := c (c^3 - c …
answered Nov 12 '16 by Chris K
When you solve the differential equations to tmax=2000, the only way s0 can go beyond that time is by extrapolation, which easily goes wild. Look at this, where the valid solution is green and the ex …
answered Apr 27 '17 by Chris K
The pseudo-arclength continuation function TrackRootPAL I hacked together here works on this problem. First, define TrackRootPAL from that link. Then start at your two initial points to get two trac …
answered Aug 10 '16 by Chris K
Not an answer, but an extended comment. I am not sure there is a periodic orbit in your implementation of this system in Mathematica. Plot[Evaluate[x[1.303900184464743, 3.81159928041479][t] /. solp] …
answered Jan 21 '18 by Chris K
This doesn't really address OP's question, but in response to @MarcoB's comment, here's a much easier way to simulate the dynamics and find cycles based on Nest: q = 2.382163 - 2*0.8390658634208773 - …
answered Mar 1 '17 by Chris K
As @Lotus suggested, I think RandomFunction and ItoProcess are what you need. τ = 1; ga = gb = 1; σ = 0.7; τs = 100; sol = RandomFunction[ItoProcess[{ \[DifferentialD]r[t] == \[DifferentialD]t/τ* …
answered Oct 4 '17 by Chris K

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