Questions tagged [numerical-methods]
Questions on numerical methods; methods for approximately solving various problems that often do not admit exact solutions. Such problems can be in various fields. Numerical methods provide a way to solve problems quickly and easily compared to analytic solutions.
14,527 questions
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Is this recurrence for $\pi$ with order $2m+1$ already known? [closed]
Recurrence formula for $\pi$ with convergence order $2m+1$:
$$
x_{n+1} = x_n + \sum_{k=1}^{m} \left[ (-1)^{m+k} \cdot \frac{1}{k} \prod_{\substack{j=1 \\ j \ne k}}^{m} \frac{j^{2}}{k^{2} - j^{2}} \...
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What is the length of the height AH?
I'm trying to find a problem about right triangles with a minimalist statement that isn't too obvious. Here's what I've come up with :
ABC is an A–right triangle, H is the orthogonal projection of A ...
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Richardson Extrapolation to the highest possible accuracy to evaluate a function derivative
I am given f(x)=cosh(x) and asked to estimate f’(0.6) using Richardson Extrapolation to the highest possible accuracy. I computed the centered difference using h1=0.2 and h2=h1/2=0.1
I got
D(0.1)=0....
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What would be the recommended approach to compute line integral in the 2D plane?
I have a certain dataset which contains $x-y$ components of a vector quantity $\vec{F}$. The $x-y$ points are such that they essentially discretize a curve which encloses the origin. I want to compute ...
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What's the pattern behind the algorithm of repeatedly taking a number and subtracting its reverse digits?
The algorithm is quite simple. Let's start with some definitions.
Take an integer $k$ of length $N$ we can denote its digits from left to right as $k=k_0k_1... k_{N-1}$.
Now let $k_{rev}$ be the ...
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Quadrature rule for tensor product of fourier basis
For reasons not directly relevant to the question, I am constructing a function basis in $\mathbb{R}^3$ by taking the tensor product of the fourier basis (up to discretization).
I must now come up ...
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Which type of numerical differentation (forward, backward, central) is better suited for magnetic field data
We have three types of basic numerical differentation: Forward, Backward and Central defined as such:
Forward difference (uniform grid)
$\frac{df}{dt}\Big|_{t = t_i} \approx \frac{f_{i+1} - f_i}{\...
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Relation between companion matrix, characteristic polynomial, and points where time waveforms of a system become zero
I want to pinpoint the times where an output waveform of an electronic circuit has a specific value. This is a root-finding problem but to my knowledge root finders don't guarantee to find all roots ...
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How can I smooth noisy experimental data while preserving the overall shape and monotonic trends of the curve?
I have several sets of experimental data representing borehole diametrical closure versus distance along a borehole.
Each dataset shows a general smooth trend (for example, a small increase followed ...
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numerical methods for conformal mapping: overview
I am trying to get an overview of "all" (usable) numerical conformal mapping methods, and here is what I found/ read up on so far. Anyone who is an expert in the field who wants to correct/ ...
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Diffusion equation after one time-step
Consider the equation:
$$
\partial_tu=D\partial_{xx}^2u
$$
with reflecting boundary condition at $x=0$ and with $u(x,0)=\delta(x)$ as an initial distribution.
First question: How should I understand a ...
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How good is computing $\left\|f\right\|_p$ with large $p$ as a numerical approximation for $\left\|f\right\|_{\infty}$ for functions $f$?
Let's suppose that I wanted to compute $\left\|f\right\|_{\infty}=\sup_{t \in \mathcal{T}} \left|f(t)\right|$ for a $f$ that may not be easy to optimize. This is the infinity norm of a function, and ...
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Why are my PDE residuals so large when using finite-difference method? [closed]
I’m computing PDE residuals for the The Well datasets (for example turbulent_radiative_layer_2D and shear_flow) using finite-difference methods, but the results are much larger than I expected. ...
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Numerical vs exact antiderivative using Fourier spectral method
I'm trying to compare my numerical vs exact solution to the anti-derivative of the piecewise function $$u(x)=\begin{cases}1,&x<\frac{\pi}{2}\\2,&\frac{\pi}{2}\leq x<\frac{3\pi}{2}\\1,&...
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$H^1$ functions and continuity
I’m sorry if this has already been answered; I couldn’t find a clear answer (maybe there is an indirect one and I failed to make the connection).
In the context of numerical analysis / finite elements ...