2,205 questions
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Why doesn’t the barycenter method detect subpixel displacements where correlation does?
I’m working with X-ray imaging data.
I have a reference image containing a structured pattern, and a sample image where this pattern is slightly distorted due to the presence of a physical sample.
My ...
- 111
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votes
1
answer
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Cutover point between two CDF implementations
My goal is to implement a CDF (cumulative distribution function) for the Standard Normal Distribution and to do so with the best possible numeric accuracy.
This is my starting point: (1 + erf(x / sqrt(...
- 227k
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votes
5
answers
230
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Why no floating point error occurs in print(0.1* 100000) vs (Decimal(0.1)*100000) due to FP representation of 0.1?
I am studying numerical analysis and I have come across this dilemma.
Running the following script,
from decimal import Decimal
a = 0.1 ;
N = 100000 ;
# product calculation
P = N*a
# Print product ...
2
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2
answers
97
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Find correct root of parametrized function given solution for one set of parameters
Let's say I have a function foo(x, a, b) and I want to find a specific one of its (potentially multiple) roots x0, i.e. a value x0 such that foo(x0, a, b) == 0. I know that for (a, b) == (0, 0) the ...
- 531
-1
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18
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PySHtools library script
I have two perfectly defined sets of SH coefficients obtained through rigorous models in two text files.
I have read that PyShtools has the necessary classes and functions to plot them in a restricted ...
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0
answers
53
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Phase Portrait of Coupled ODEs Not Matching Expected Graph in Python (SciPy)
I’m trying to generate a phase portrait for a system of coupled ordinary differential equations (ODEs) using Python’s scipy.integrate.solve_ivp. The system models the frequency of cooperators (x) and ...
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1
answer
50
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Producing bifurcation diagram of logistic map including unstable points
I'm trying to produce a bifurcation diagram such as this one.
Typical bifurcation diagrams only include stable fixed points, which are attractive (nearby points get pulled towards the fixed point upon ...
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1
answer
62
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Difference in output of sympy.binomial vs scipy.special.comb
Why does the following code that calls comb produce the wrong output?
from scipy.special import comb
from sympy import binomial
def coup(n=100, m=10):
expectation = 0
for j in range(1, n + 1):
...
- 2,599
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0
answers
24
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multivariate Fox-H numerical computation
I have some troubles in numerically calculating PDF below:
SNR of particular system model
This PDF is the expression of SNR of practical RIS-aided system: https://ieeexplore.ieee.org/document/9387559 (...
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answers
29
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Partial derivative of logistic function for Levenberg-Marquardt
I am trying to write code that will fit logistic function to set of data. I am using Levenberg-Marquardt routine (as given in Numerical Recipes 3rd edition) and that requires me to supply a function ...
- 2,658
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1
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119
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Smooth numerical AND function with N > 2 parameters for a C++ optimization engine
Consider an optimization engine that uses target functions and constraints that requires smooth functions (with at least first-order continuous derivative) to work well.
Now consider a boolean ...
- 351
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45
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How to simulate in python the superconducting density of states of a BCS superconductor with YSR (yu-shiba-rusinov) with 1D chain tight binding model
I try to simulate the following problem:
Compute the density of states numerically of a BCS superconductor with magnetic impurities using the tight binding model of 1D chain with periodically border ...
0
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0
answers
80
views
Minimum image convention for a MD simulation in Python
I'm trying to implement a simple molecular dynamic simulation in Python for N atoms with periodic boundary conditions using minimum image convention.
Here is my code:
import numpy as np
import ...
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0
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33
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Simple MD simulation for N atoms with PBC in Python
I'm trying to implement a simple molecular dynamic simulation in Python for N atoms with periodic boundary conditions while allowing coordinate wrapping to visualize the atoms interacting through
...
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0
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1
answer
65
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Molecular dynamic simulation using velocity verlet in Python
I'm trying to implement a simple MD simulation in Python (I'm new to this),I'm using LJ potential and force equations along with Verlet method.
I posted another question about the same code yesterday ...
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