All Questions
Tagged with undocumented differential-equations
15
questions
6
votes
1
answer
161
views
Understanding NDSolve::ndmmc
When running NDSolve with Method->{"EquationSimplification" -> "MassMatrix"} I frequently encounter ...
- 547
1
vote
1
answer
190
views
Trapezoidal method for ODE results in cmsing warning
I try to solve an ODE using the trapezoidal method. I do the following (Definition of Trapezoidal is from this answer):
...
- 605
4
votes
0
answers
83
views
Is there more complete documentation of DSolve with all hacks?
I know DSolve. I know this community and I am able to gather some hacks.
There is this:
...
- 4,098
8
votes
1
answer
228
views
Available Methods for DSolve?
I would like to know, apart from Method->Automatic what are available methods for DSolve.
...
- 299
5
votes
0
answers
65
views
What are the valid options for the "ParametricCaching" option in ParametricNDSolve?
I am using ParametricNDSolve as part of the calculation of an objective function for an optimization, so I am trying to strike a balance between memory usage and ...
- 15.3k
2
votes
1
answer
174
views
How to set MaxStepSize for the case of two variables
The option MaxStepSize permits to manually set the step size of the integration in NDSolve and similar functions.
How do I set ...
- 6,757
5
votes
1
answer
342
views
NDSolveValue and pdepe of MATLAB disagree under spherical coordinates
Assuming there is a spherical activated carbon particle, the concentration outside the grain is 200 (C[t,ri] == 200), that ...
- 53
11
votes
1
answer
258
views
What's the solver behind Method -> {“EquationSimplification” -> “MassMatrix”}
Related: What's behind Method -> {“EquationSimplification” -> “Residual”}
By reading the document carefully, I've learnt that there are 3 possible options in "EquationSimplification" ...
- 1,461
4
votes
1
answer
220
views
TemporalDiscretization in MethodOfLines
When solving ODE's one can use options like MaxStepFraction to control the number of grid points.
When solving PDE's ...
user67126
6
votes
1
answer
168
views
How to vectorize this nonlinear ODE system for NDSolve?
I learned a long time ago that NDSolve can often be sped up by vectorizing systems of equations. I've got a problem now that seems ideal for this approach, but I ...
- 20.3k
8
votes
1
answer
191
views
Can we construct our own NDSolve`StateData?
NDSolve can be broken into three stages:
NDSolve`ProcessEquations processes the equations and sets up an NDSolve`StateData ...
- 20.3k
11
votes
0
answers
184
views
How to modify NDSolve`StateData without crashing the kernel?
Probably a hard question, but it's better to cry out loud.
Reminded by Chris K, I noticed my fix function has been broken since v11.3. After some checking, I ...
- 67.1k
12
votes
3
answers
1k
views
Reduce ODE into 1st order
I have an explicit set of differential equations:
$ \ddot{x}=f(x,\dot{x})$
I would like to reduce it in the following way:
$ \dot{y} = g(y)$
by substitutions as shown here: wikipedia. I have done ...
- 2,202
16
votes
1
answer
545
views
"ParametricSensitivity" in ParametricNDSolve
"ParametricSensitivity" is listed as a Method in the documentation for ParametricNDSolve, ...
- 61.8k
16
votes
2
answers
2k
views
The only usage for the option InterpolationOrder in NDSolve is to be set to All?
We know that changing the option InterpolationOrder in ListLinePlot、ListPlot3D、...
- 67.1k