Stack Overflow
Stack Overflow

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
20
votes
1 answer

Discretized continuous Fourier transform with numpy

Consider a function f(t), how do I compute the continuous Fouriertransform g(w) and plot it (using numpy and matplotlib)? This or the inverse problem (g(w) given, plot of f(t) unknown) occurs if there exists no analytical solution to the Fourier…
thomasfermi
  • 1,183
  • 1
  • 10
  • 20
9
votes
2 answers

Fourier transform a trig function in Sympy returns unexpected result

I think Sympy makes a mistake in calculating the Fourier transform of a trig function. For example: from sympy import fourier_transform, sin from sympy.abc import x, k print fourier_transform(sin(x), x, k) The expected answer via Mathematica is…
Kattern
  • 2,949
  • 5
  • 20
  • 28
8
votes
1 answer

Continuous Fourier Transform with Python / Sympy (Analytical Solution)

I recently replaced Matlab with Python because I was real;y excited by Sympy. But now I have the following problem: I need a way to reliably calculate continuous fourier transforms with Python. Sympy has problems with solutions including Diracs…
oeh
  • 83
  • 1
  • 5
6
votes
2 answers

Fourier Transformation vs Numpy FFT

This is probably a very naive question but here it is. I want to calculate Fourier transform of a function f(x). So I define a numpy array X and pass through vectorized function f. Now if I calculate the FFT of this array f(X) it does not come out…
The Imp
  • 187
  • 1
  • 10
4
votes
2 answers

Fourier Transform Using Numpy

I'm trying to calculate the Fourier Transform of the following Gaussian: # sample spacing dx = 1.0 / 1000.0 # Points x1 = -5 x2 = 5 x = np.arange(x1, x2, dx) def light_intensity(): return 10*sp.stats.norm.pdf(x, 0,…
Luke Polson
  • 434
  • 6
  • 14
4
votes
1 answer

Why doesn't sympy simplify the Fourier Transform of a derivative?

We know that the Fourier Transform of a derivative is where k is the fourier variable. Explanation here My question is, why doesn't sympy use this knowledge? For example: from sympy import Function, symbols, fourier_transform, Derivative f =…
tBuLi
  • 2,295
  • 2
  • 16
  • 16
4
votes
1 answer

Returning 'traditional' notations of functions in the context of fourier interpolation

in numerical analysis we students are obligated to implement code in R that given a function f(x) finds its Fourier interpolation tN(x) and computes the interpolation error $||f(x)-t_{N}(x)||=\int_{0}^{2\pi}$ $|f(x)-t_{N}(x)|^2$ or a variety of…
DwayneHart
  • 129
  • 1
  • 7
3
votes
1 answer

I want to reduce the time to compute 2D FFT in C++ on 100 million complex data

I am trying to compute 2D FFT on 100 million complex data (100000x1000) and it is taking 4.6 seconds approximately, but I want to reduce time. Then I tried to compute it using fftw_thread. But then the computation time has increased (in 2 threads…
Siddhartha Roy
  • 59
  • 1
  • 4
3
votes
1 answer

Interpreting Prophet Output for Weekly and Yearly Seasonality

I am going through the tutorial for using prophet in R. You can find the dataset here: https://github.com/facebookincubator/prophet/blob/master/examples/example_wp_peyton_manning.csv # R library(prophet) library(dplyr) df <-…
nak5120
  • 4,089
  • 4
  • 35
  • 94
3
votes
1 answer

When is the Fourier transform of a signal periodic?

Also , is the inverse Fourier transform of a periodic signal also periodic ?
hakunamatata
  • 127
  • 1
  • 14
2
votes
1 answer

Inaccurate Fourier Transform using Python

I am aiming to take the fourier transform of a distribution. It is a physics problem and I am trying to transform the function from position space to momentum space. I am however finding that when I attempt to take the fourier transform using scipys…
George
  • 232
  • 1
  • 2
  • 20
2
votes
1 answer

Finding Fourier coefficients algorithm

Ok, so I have been trying to code a "naive" method to calculate the coefficients for a standard Fourier Series in complex form. I am getting very close, I think, but there are some odd behaviors. This may be more of a math question than programming…
rocksNwaves
  • 5,331
  • 4
  • 38
  • 77
2
votes
1 answer

plot Fourier expansion with gnuplot

After computing the Fourier coefficients of my function, I'd like to plot the first terms of the serie. However, I can't get the correct result… It's not a matter of wrong coefficients as it plots…
NBur
  • 159
  • 3
  • 10
2
votes
1 answer

Matlab not plotting the exact fourier signal

I'm trying to plot a simple signal in fourier domain using Matlab. It's not plotting the correct signal. Here is my code: clc; clear all; close…
Bharat
  • 1,044
  • 15
  • 34
2
votes
1 answer

why do we need time sampling to plot a stationary signal?

I am new to matlab and signal processing. I have wrote the below posted code. what i could not understand is, the time soecification section at the beginning of the code. I do not why do we need sampling when specifying an interval or time duration,…
Amrmsmb
  • 1
  • 27
  • 104
  • 226
1
2 3 4 5