Questions on the use of numerical functions NIntegrate and NDSolve.
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0answers
45 views
Some boundary issue of Integration
When I try to solve the integration f(x) as following (type it in the Mathematica)
$ f(x)= \frac{1}{π} \int_{-1}^{1} \frac{\sqrt{1-y^2}}{(y-x)}dy $,
I met some boundary problems.
I have searched some ...
-2
votes
0answers
52 views
Nintegrate for single point
For $f(x)=e^x$ we have:
$F(x)=\int f(x) dx=e^x+C$
I consider $C=0$. For $x_1=2 \text{ and } x_2=3$, we can compute:
$S_1=F(x_1) \text{ and } S_2=F(x_1)+F(x_2)$
In Mathematica we have function ...
-2
votes
0answers
51 views
Trying to reconcile solution from NDSolve with analytic solution
I am very confused aboutFindFit. I have an ODE that I solve withNDSolve...
0
votes
1answer
97 views
0
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0answers
46 views
Inversion algorithm for Laplace Domain
I'm trying to invert an equation in the Laplace domain using Stehfest algorithm. It works very fine, but since I'm trying to represent a sinusoidal behavior I need a different algorithm that makes use ...
1
vote
0answers
29 views
why maxrecursion didn't work if I specify singularity in NIntegrate
I study sigularity specification and MaxRecursion in NIntegrate. And find something unusual.
first I define a function
δ[x_, y_: 1/100] := 1/π*y/(x^2 + y^2)
...
3
votes
1answer
114 views
Why this numerical integration takes so long?
Let me explain the problem. I am trying to integrate a one dimensional integral:
$$\int {g\left( {{k_x}},parameter1,parameter2,...\right)d{\mkern 1mu} {k_x}} $$
for the sake of clarity, I will give ...
6
votes
1answer
74 views
Mathematica9: NDSolve slows down after repeated calls
I have noted that in Mathematica 9 my code, which involves a lot of calls to NDSolve, slows down considerably after some time.
Apparently, the problem is NDSolve itself and it seems to be related to ...
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
...
4
votes
2answers
199 views
2
votes
1answer
72 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 ...
5
votes
1answer
98 views
How to demonstrate lack of stability with advection equation
I am trying to that using a coarse grid with an explicit method for, say, the advection equation leads to an unstable solution. The trouble is Mathematica avoids unstable solutions with good ...
2
votes
1answer
78 views
Evaluating function only when its optional argument is numeric
I want to have the argument 'a' for myf2 in form of optional argument, but at the same time I need to evaluate the function only if 'a' is Numeric, see also my previous question.
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1
vote
2answers
84 views
NonlinearModelFit with NDSolve [duplicate]
I have a function which uses NDSolve and evaluates the resulting InterpolatingFunction at point [10]:
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3
votes
0answers
97 views
Crank-Nicolson with NDSolve?
As far as I understand, the Crank-Nicolson method (a.k.a. trapezoidal method) can be expressed as a second order implicit Runge-Kutta method. It's Butcher tableau is:
...
