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Questions tagged [continuous-fourier]

Use this tag for questions about computation of exact continuous-time Fourier transform (e.g. using symbolic software like Sage, Mathematica, Sympy). For the discrete Fourier transform and fast Fourier transform, use tag [fft].

63 questions
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Determining the interval of event occurrence in timeseries

Given different binary time series (zero shows no event, 1 shows the occurrence of an event), we can see the intervals at which the event occurs in the first plot is higher than the second and last one. I wonder if I could use scipy statistics or…
Seji
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how to separate white guassian noise from signal in foureir domain

i have a signal with added white gaussian noise. i m doing some kind of mode decomposition. After mode decomposition the noise does not look random but have streaks like appearance in time domain. The mode decomposition is a wiener filter and it…
sal abb
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Is there a mistake in the sympy fourier_series?

Good morning, I am trying to compute the Fourier series of f=x (periodic in 0
Francesco
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Does fourier_series only work if the function is symmetrical along the y axis?

Good morning, I am trying to create a fourier series of a triangular wave through sympy. The period is from 0 to 1, with f=0 in x=0 and f=1 in x=1. The code is below. However, it seems as if fourier_series automatically assumes that f=0 in the…
Francesco
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Plot a fourier transform of a sin wav with matplotlib

I am trying to plot a fourier transform of a sign wave based on the scipy documentation import numpy as np import matplotlib.pyplot as plt import scipy.fft def sinWav(amp, freq, time, phase=0): return amp * np.sin(2 * np.pi * (freq * time -…
Sam
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calculating DFT of time signal in MATLAB

This code computes the DFT from time domain. Can anybody see the code below and help me to get the right answer? my problem is: when I change N value, for example, to 4, 5, 10 ,or other values. X(1) changes with that. but I think X(1) must be the…
Sanaz Darzipour
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How can I read an Elliptical Fourier Descriptor from SHAPE under the Momocs package of Rstudio?

I wish to load a CHC or NEF file from the SHAPE software in order to read the contours under MOMOCS and make the related analyses (Plot, PCA...) I have difficulties under R as well as under the package. How should I proceed? Here is an extract of an…
Gordianknot
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how to optimize the best value for 'k' in FourierSeries

I am try to forecast 700 different product using autoARIMA in pmdarima package. For seasonality, Fourier Series makes it easier, because all products pattern are different. But, how can I select different values of "k", based on product in a loop.…
Maddy
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Fourier Sine Series issue: Dot indexing is not supported for variables of this type

Here is my code: clearvars; clc; close all; %Define the domain: l=1; %and consider, say, 4 periods x=linspace(-4,4); %Define the number of terms to consider n_tot=50; %Initialize the vectors containing each term of the…
Ryan Krieger
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How to evaluate sympy piecewise-like expressions so it's easy to obtain numerical only output?

I have the following code which is part of a practice I'm working on: Here is a function that obtains 2*N+1 coefficients of the Fourier series for the input function "ft" written in terms of sym.Heaviside(t), the goal is to get from this function…
ego2509
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Using fft to extract frequency

I have a signal which is a linear combination of two frequencies and I am trying to use MATLAB to determine what frequencies the (main) signal consists of. As an input I have the sample rate, rate and a row vector with the signal data, segment. Now…
Mathbeginner
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Fourier transform of a Gaussian function in Python

I want to calculate the Fourier transform of some Gaussian function. Consider the simple Gaussian g(t) = e^{-t^2}. The Fourier transform of g(t) has a simple analytical expression , such that the 0th frequency is simply root pi. If I try to do the…
user1887919
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ifourier command not giving expected results?

I am reading a book of Alex Palamides, chapter 6, Fourier transform and I am trying to compute the inverse transform of a function, but when I write the code provided in the book in MATLAB, I do not get the expected answer, as written in the…
LECS
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Roadmap from sensor data to predictive maintenance

I am new about these topics. I research a lot of article about this issue. There are a lot of different techniques. But I am confused, because I don't know, where to start. According to my research, first important thing; I must make preprocessing…
özlem bulu
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Plotting a symbolic Fourier series

I've written code for a Fourier series. This is what I have so far: function FS = FourierSeries(f,degree) cosCoefficients = zeros(1,degree); sinCoefficients = zeros(1,degree); syms x; a0 = double((1/pi)*int(f,-pi,pi)); for n = 1:degree …
Sharon
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