110 questions
1
vote
1
answer
48
views
invertlaplace() function makes abnomal calculations
I'm working currently on an analytical model for of a pressure transient well-test (build-up). Using formula from Lake's Petroleum Engineering Handbook Vol. 1,
which describes pressure change in ...
- 11
1
vote
0
answers
46
views
Having problems with diffraction pattern generation in mathematica
I am unsure about the results, but is it possible to generate diffraction pattern like following in the second picture. The following equation is like this added in the first picture for different ...
- 11
0
votes
0
answers
121
views
Modified Bessel function ratios
How can I handle BesselI(0,a)/BesselI(0,b) to prevent NaN in Fortran or MATLAB?
I expect a method of simplifying the ratio or a mathematical trick to handle the problem. I try a series representation ...
-1
votes
1
answer
68
views
BesselJ in .net accord can't accept complex number
I want to pass complex number to bassel function in .net as you can see :
Complex[,] F_k = new Complex[M, N];
F_k[m,n] = ((2 * Bessel.J(1, new Complex(1, -1) * (2 * 0.0110/ 122))));
but I get this ...
- 7,357
1
vote
1
answer
360
views
zeros of the derivative of the spherical Bessel function
I make reference to the function in Scipy here. I want to calculate the zeros of the derivative of the function j'_n(x). Any propositions for how to do it ?
- 369
0
votes
0
answers
103
views
Using Bessel function in a shader in Unity
I'm trying to access Bessel function J0 in a shader in Unity.
I haven't found any built-in function that does the job.
I have calculated 10 000 points of the J0 via python and stored them in a .txt
...
0
votes
0
answers
89
views
Calculation dimensionless time function thermal coductivity?
Currently I am trying to do some experiments to try to determine thermal conductivity of my fluid which is ethanol.
To do so, I need to use the principle of TPS method which correspond to the kind of ...
- 1
0
votes
1
answer
392
views
Reimplementing Bessel Function in Fortran Function Causing Infinite Looping
So as an assignment I was given the task to write a function that when given an x, calculates the corresponding first order Bessel function from it. The equation is as follows: https://youtu.be/...
- 15
0
votes
2
answers
239
views
Why does Bessel function in Scipy and EXCEL give different results?
I tried to use Scipy and EXCEL to calculate Bessel function, but they give different results. Do you know why? Thanks in advance.
Python code:
import scipy.special as ss
result = ss.k1(0.2155481626213)...
- 539
0
votes
0
answers
447
views
Fortran errors - Complex argument bessel function
I have been having some trouble getting some fortran code I was given working. This code uses an external library, NUMERICAL_LIBRARIES, by Rogue Wave in order to implement a bessel function with ...
- 1
0
votes
1
answer
850
views
Polar plot in Matplotlib by mapping into Cartesian coordinate
I have a variable (P) which is a function of angle (theta):
In this equation the K is a constant, theta_p is equal to zero and I is the modified Bessel function of the first kind (order 0) which is ...
- 519
0
votes
1
answer
1k
views
Is there a specific R function for the derivative of modified Bessel function of the second kind?
My problem is as it says in the title, I am trying to use the derivative (with respect to v) of the modified Bessel function of the second kind K_v(x) but with no success.
I read in one of the ...
- 373
0
votes
0
answers
234
views
Modified Bessel function with Infinite sum in R
I am trying to implement the following formula in R where r0, t, theta0 and alpha are constants. Also, I is a Modified Bessel function of the first kind. My issue, I suppose, is from the Sum term to ...
- 11
0
votes
0
answers
225
views
How can I save and reuse the results of the FFT applied on an image to calcuate the bessel potential?
Please can you help me correcting this code? I want to save the result of the Fast Fourier Transform of each image apart so I can reuse the proper coefficients for every band of wave I get from the ...
- 1
0
votes
1
answer
73
views
Plotting function with a summation produces a wrong result
I have an equation that needs to be plotted, and the plot is coming out incorrectly.
The equation is as follows:
And the plot should look like this:
But my code:
clear; clc; close all;
eta = ...
- 73
0
votes
1
answer
2k
views
Finding the nth root of the bessel function of the first kind (J0(x)) using bisection
First of all, I would just like to clarify that this is an assignment for school, so I am not looking for a solution. I simply want to be pushed in the right direction.
Now, for the problem.
We ...
- 167
-1
votes
1
answer
694
views
Problems with computing Integral in Python
So I've been trying to use the general integration method (quad) from Scipy on numpy on a specific expression; however, I get the following error
TypeError: unsupported operand type(s) for *: '...
- 155
1
vote
1
answer
520
views
Kelvin function KelvinBer[n,z] in Python
In Mathematica there is the Kelvin function KelvinBer[n,z]. I would need something equivalent in Python with n=0 and n=1.
There is scipy.special.ber(x), but as I understand it and played around, it ...
- 222
2
votes
1
answer
350
views
How to plot in matlab using the besselh function with a given range of k (reduced frequency)?
I am using a Matlab function called besselh which gives an exact solution to Theoderon's lift deficiency function for a two-dimensional airfoil executing a simple harmonic motion in incompressible ...
- 179
3
votes
1
answer
549
views
Why does scipy bessel root finding not return roots at zero?
I am trying to use code which uses Bessel function zeros for other calculations. I noticed the following piece of code produces results that I consider unexpected.
import scipy
from scipy ...
- 55
1
vote
2
answers
399
views
matrix of special (besselj) functions
I'm new to julia so I would welcome some advice to improve the following function,
using SpecialFunctions
function rb(x, nu_max)
bj = Array{Complex64}(length(x), nu_max)
nu = 0.5 + (0:nu_max)
...
- 193
0
votes
0
answers
357
views
Advice on method to integrate Bessel functions in C++ [duplicate]
I need to integrate an oscillatory function of this kind:
where I have a Bessel function which is oscillating, while F is not very oscillatory. I am looking for the most precise/accurate method to do ...
- 1,343
0
votes
1
answer
506
views
Integrating special function and plotting
I am trying to plot an integration of a special (eg. Bessel) function and my minimal code is the following.
#!/usr/bin/env python
import matplotlib.pyplot as plt
import numpy as np
import scipy....
- 2,394
0
votes
1
answer
111
views
Handling large numbers and precision of Ricean Fading PDF python
I'm trying to calculate Ricean Fading PDF using following equation. RIcean Fading PDF. where 'y' is normalized envelope and 'gamma' is SNR
if the K value is large, then
math.exp(-((1.+_gamma)*pow(...
- 3
1
vote
1
answer
405
views
Compiling of complex_Bessel_function library - linking with Fortran code - mex file
I have made a .cpp code that uses the following online library:
Complex_Bessel_functions.
I want to make a .mex file out of my code. When I am typing:
mex GUSTAVsolution.cpp
Matlab gives the ...
- 31