Tagged Questions

Questions on the symbolic (DSolve, DifferentialRoot) and numerical (NDSolve) solutions of differential equations in Mathematica.

221 views

NDSolve mixing many scalar and vector equations

I have a set of scalar equations in many unknowns, which I want to combine with a vector equation inside an NDSolve. The equations are a mix of differential and algebraic equations. A set of scalar ...
47 views

“MemoryAllocationFailure” in DSolve

Mathematica 10.4, Windows 10, 6 GB RAM, 64 bits When I trying to solve DSolve[{v'[t] == 100 - 0.15 v[t]^2, v[0] == 30}, v[t], t] I get ...
327 views

What can one do with extremely stiff problem in NDSolve?

Consider the following illustrative problem: $$\frac {\partial f} {\partial t} = \frac {\partial} {\partial x}(x f) + \frac {\partial} {\partial x}(f \frac {\partial f} {\partial x})$$ This is ...
46 views

Clearing Problem with DSolve

Consider: This is a classic mistake (using a single equal sign) that has been discussed on Mathematica Stack Exchange before. I know that Clear[Derivative] will cure the problem. However, consider ...
42 views

NDSolve point animation not working [closed]

The below code plots the path of a ball bouncing but loses 90% of its velocity each time it bounces. (adapted from https://reference.wolfram.com/language/ref/WhenEvent.html). ...
59 views

I am having trouble with the DSolve function [closed]

DSolve[{x''[t] + 0.01 x'[t] + x[t] == E^(It), x[0] == 1, x'[0] == 1}, x[t], t] This give the following error :"Equation or list of equations expected instead ...
66 views

How to change the boundary condition near singularity

The following system has a singularity around $x=0.451$. What I want to do is to detect when the solution gets close enough to this singular point (in this example I'm using the threshold of $0.001$), ...
56 views

DSolve does not give an analytic solution for a tutorial input [closed]

I am just starting with Mathematica and I have tried to solve PDE following DSolve, with first three inputs from the Elliptical Partial Differential equations ...
68 views

Nonlinear PDE system in a rectangle

This question is posted by two physics students working together. We are having some trouble while trying to solve Navier-Stokes equations, The main problem is that, while our set of partial ...
102 views

Plotting graphical analysis of chaotic behavior

I am trying to plot some results of chaotic behavior in a system based on a paper for one of my classes. I am a physics undergrad. I found some sample code online springy.nb which I have been trying ...
93 views

How to omit the corrupt value in a program?

I've such errors: Coordinate .. is not a floating-point number and can't correctly fix it. The problem occures when x==Log[2] The program works correctly ...