Questions on the symbolic (DSolve, DifferentialRoot) and numerical (NDSolve) solutions of differential equations in Mathematica.
4
votes
1answer
110 views
Modelling a Rocket Launch using NDSolve
I'm trying to model a rocket launch with Mathematica but I've run into a little problem since I don't know how to turn the thrust off. I'm using Newton's Law of Universal Gravitation plus an added ...
-1
votes
0answers
70 views
Can't solve “a particle in a box” problem! Have an error [on hold]
Vo[X_] := Which[x < 0, Infinity, 0 <= x <= L, 0, L < x, Infinity]
eqn = (-\[HBar]^2/2/m) D[Ψ[x], {x, 2}] + Vo[x]*Ψ[x] == e*Ψ[x]
DSolve[eqn , Ψ[x], x]
...
3
votes
1answer
55 views
Create ParametricFunction object without ParametricNDSolve
Documentation of v9 states that ParametricFunction is generated by ParametricNDSolve and ...
0
votes
1answer
128 views
Bifurcation diagrams for system of equations
I am interested in constructing a bifurcation diagram for parameter a in the dynamical system given in the code below. I want to see how parameter changes affect the stability of the system. The ...
0
votes
1answer
85 views
extract data from the solution of a ODE [on hold]
I want to fit the solution of my ODE. How can I extract the data points from the solution? It's explained here.
As an example we have this:
...
0
votes
1answer
76 views
Can graph interpolating function, but not use it. Any thoughts?
When solving a system of differential equations numerically, I get two interpolating functions. I can graph both of these, but when I try to evaluate either of the functions at a point, it just spits ...
0
votes
2answers
108 views
Interpolating a ParametricFunction
Original domain of my independent variable t is 0 to 10 nanometers, but in Mathematica (as in most numerical software), it's good idea to solve differential ...
1
vote
0answers
60 views
NDSolve for a large system of coupled (complex valued) ODEs
The system under consideration here is a generalization of the one I discussed in this problem. Qualitatively, I am trying to solve a system of coupled nonlinear (up to order 4 in the dep variables) ...
3
votes
1answer
75 views
Changing a wave simulation
I want to adjust some code that I found on this Wolfram Demonstration: http://demonstrations.wolfram.com/WaterRipplesPassingThroughASlit/
Basically it shows a wave passing through a single slit. I ...
2
votes
2answers
80 views
Ploting a 3D vector field using Manipulate, VectorPlot3D and NDSolve
My aim is to plot a vector field of the following system with a few trajectories:
$$r'(t)=i-l.r(t)-\text{ux}. r(t). x(t)-\text{uy}. r(t). y(t) \\ x'(t)=\text{ex}. \text{ux}. r(t). x(t)-\text{mx}. ...
3
votes
0answers
35 views
NDSolve: ProcessEquations and Reinitialize with Piecewise functions
I am having trouble with using NDSolve`Reinitialize when the system consists of a pieceise function.
If we define the ODE system
...
1
vote
1answer
51 views
3D Phase Portrait with direction fields and sample solution curves [duplicate]
I have seen NDSolve and ParamtericPlot3D used for things like the Lorenz Attractor, but was wondering if there is a way to draw a 3D phase portrait for a system.
Something akin to this: ...
2
votes
0answers
116 views
Having Mathematica solve or help solve a set of 8 equations
There is a set of DDE's that arise in leukemia dynamics and I'd like to find the equilibrium points of the system by setting all of the derivatives equal to zero. The system can be described in ...
2
votes
1answer
116 views
Problem in solving PDE
I have a problem in solving a type of PDE. The actual problem involves diffusion and adsorption in a trench, but here is a simpler example. I have two independent variables $t$ and $x$. There are two ...
2
votes
1answer
71 views
Limitations of ParametricNDSolve family w.r.t objective functions
Observation:
I can see even for very simple modification in case of an scalar objective involving an definite integral in time ParametricNDSolve fails. Here is an ...
