# Questions tagged [convolution]

For questions about applying convolutions to data. This can include the process of convolving two functions together or seeking a kernel matrix to convolve with a grid of data (often done in image processing).

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### Convolution in Fourier space with Python

I am trying to implement following step into the my cosmological particle mesh code. From the PM code, I obtained the 3D array for density and used the following code in python, but I'm not sure, if ...
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### Is the following the correct implementation of VGG network?

As exercise I am implementing few fundamental networks. Specifically right now I am implementing VGG The code I've got at the moment is the following: class MyVGG(nn.Module): ...
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### How expensive is it to compute an image convolution

I was wondering how computationally expensive it is to compute an image convolution. That is, to convolve an NxN image with a 3x3 or 5x5 convolution filter? It seems like this would be a costly ...
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### difference in notation of integral operator

I'm reading paper 1 and on page 4 they define the integral operator $\mathcal{K}$ as $$(\mathcal{K}(a;\phi)v_t)(x) := \int_D \kappa(x,y,a(x),a(y);\phi)v_t(y)dy$$ Now in an another paper from the ...
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### How to plan convoluted measurements

I have a physical function $f(x)$ which I intend to measure. Problem is that I cannot read it directly, but through a response function $g(x)$ which is known to me with great accuracy and any one ...
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### Convolution/weighted average of two arrays in Python

I have an equation that I need to calculate numerically, but I am having doubts about my approach. I am cross-posting this question from Stack Exchange, because I am not getting any responses. This is ...
1 vote
210 views

### Computing convolution on non-uniform sample

How to efficiently convolve the function $h(t)=H(t)e^{-t}$ with a function $x(t)$ sampled non-uniformly, i.e. $\{x(t_0), x(t_1), ..., x(t_{N-1})\}$? $H(t)$ is the Heaviside step function, and the ...
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### Padding length and error analysis of discrete convolution by FFT

The standard algorithm for discrete convolution of two vectors $x\in \mathbb{R}^{n}$ and $y \in \mathbb{R}^{m}$ is (in essence) a FFT of the two input vectors, multiplication of the two elementwise, ...
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1 vote
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### Deconvolution of sinc function in spectrum calculation in FTS

In Fourier transform spectroscopy (FTS) I am calculating a broadband interferogram (e.m. frequency 190-300 GHz top-hat), then back-retrieving the spectrum by FT. Here in the figure, you can see the ...
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### Why not use the convolution theorem for explicit timestepping?

Consider the advection equation $$\frac{\partial C}{\partial t} + u\frac{\partial C}{\partial x} + v\frac{\partial C}{\partial y} = 0$$ I want to do a forward time, center ...
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