# Tagged Questions

Questions on the use of numerical functions NIntegrate and NDSolve.

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### NDSolve with coupled ODE's and unknown singularities

I have two coupled ODEs that I am trying to solve numerically. It appears that there is a singularity in the solution to the equations which I am unsure how to get past. Both functions $\alpha$ and ...
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### Empty WhenEvent action crashes kernel

Bug introduced in 9.0 and persisting through 10.4.1 WhenEvent is new in 9.0. This is an example from the docs, slightly modified (action is wrapped in ...
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### Follow up: how to plot a function under NDSolve domain

Here is the details of the code to plot. ...
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### Mathematica Newmark Optimization

Here is my Mathematica code which implements the Newmark method to solve a equation of motion. The variable "ag" contains the accelerations from an earthquake record. Is it possible to optimize this ...
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### Does NDSolve iterate faster in a region where the system being solved is in equilibrium?

I was wondering how exactly the time it takes for NDSolve to iterate through a certain region of the domain depends on the local behaviour of the given system being solved. My guess would be the ...
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### Solving wave PDE

I am trying to solve the wave PDE with NDSolve. Below is the equation: ...
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### Multiply integrand with -1, and the precision changes?

"After multiplying the integrand of NIntegrate with -1, the Precision of the output will ...
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### Switching Differential Equation in NDSolve

I am trying to solve the following system of differential equations using NDSolve: $\dot{z}_t=.5(1-z_t)$ $\dot{y}_t=.05y_t+z_t-x_t$ subject to the following constraint: $-y_t-z_t\le0$ where $z_t$ ...
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### A power series expansion [closed]

Consider the function, $f(z) = z\, \tanh(\pi z) \log (z^2 + a^2)$ for some $a>0$. Now I am considering 3 different situations, $z = i(n+0.5) - i\epsilon + \delta - it$ for $n \in \mathbb{Z}$ ...
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### Integral Equation Solving [closed]

I need to solve two coupled equations such as ...
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### Take a derivative of a NIntegrate function (with two argument) [closed]

what I have is a numerical function of SBE[m,T] and I want its derivative with respect to T. Here is what I wrote, ...
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### difficulty in numerical estimate of double integral

I entered the following simple integral in mathematica: ...
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### Using a compiled function inside NIntegrate gives “CompiledFunction::cfsa” message

The following function is defined for Real input: ...
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### Problems with NDSolve for solving coupled Schrödinger-like PDEs with perfectly matched layer boundary condition

I'm trying to solve a full-vectorial wave equation for an arbitrarily shaped wave guide, by using NDSolve and perfectly matched layer (PML) conditions. The PML ...