# Tagged Questions

Questions on the use of numerical functions NIntegrate and NDSolve.

47 views

### Make integration/ plot run faster? (takes hours)

I am using Mathematica 10.0.2.0. Here is the code I am working with: ...
63 views

### How to solve in principle such coupled ODEs

One example for coupled ODEs from the Mathemtica help center reads ...
23 views

### NDSolve: Improperly assigned stepsize

This is not a question which I estimate is aided in answering by providing complete code, which is excessively long. I ran an NDSolve[] at ...
37 views

### NDSolve and piecewise functions

I'm trying to use NDSolve on a Pde for a function that is made up of several pretty complicated functions, most of which are themselves functions of an underlying piecewise function. When I try to ...
59 views

### NDSolve Step Size Effectively Zero

I'm trying to solve a PDE for a function of 2 variables. The most accurate parameterizations of this equation are very unwieldy and involve numerous piecewise elements, and so right now I'm trying to ...
16 views

### Seconde Derivatives of an integral [closed]

$$g(x) = \int_{-\infty}^{x^2/2} e^{-(x^2+1)t^2}dt\,.$$ Trouble calculating the first and the second derivative of this function.
63 views

51 views

### Error with Numerical Integration

I'm running the following code: ...
30 views

### Possible Error with the Output Graph

I'm running the following command: ...
109 views

### failure of code with Helmholtz equation with point source

I am new to the finite elements package in Mathematica. I have a system of equations, one of which is a Helmholtz equation with a point source in the interior of a bounded domain. The following is the ...
54 views

### Error with Numerical Integration and Graph Plotting

I'm trying to run the following code: ...
35 views

### Changing variable in numerical solution

I solved numerically the differential equation: ...
84 views

### Multivariate integration of a compicated expression

I have an expression in multiple variables that is something like ...
503 views

### Gillespie Stochastic Simulation Algorithm

The Gillespie SSA is a Monte Carlo stochastic simulation algorithm to find the trajectory a dynamic system described by a reaction (or interaction) network, e.g. chemical reactions or ecological ...
109 views

### Bug in the “PrincipalValue” method of NIntegrate?

Update 2 The technical support suggests setting AccuracyGoal. As I quote here It does appear that the program is returning an incorrect result along with a ...
34 views

113 views

### 2d numerical integration [closed]

I'm trying to get a numerical solution for a double integral: ...
51 views

### NDSolve for complex variables

I am trying to simulate a multiple pendulum system with damping as follows: ...
49 views

### Integration of a function of interpolating functions

I need to calculate the integral of a function of interpolating functions. Being more specific, the function I want to integrate is the following ...
59 views

### How to speed up NIntegrate when using an interpolating function output from NDEigensystem?

I have been working with NDEigensystem in order to find the resonant frequencies of different shaped drums. I would also like the coefficients of the different eigenfunctions so that each of these ...