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175
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What does np.ones_like represent in a quiver plot of a differential equation?
I found some similar questions about quiver plots and direction fields, but I’m still confused about the meaning of these two lines in many examples:
What do dx = np.ones_like(f) and dy = f mean in a ...
-2
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1
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75
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Trying to solve a satellite equation, but I'm getting an empty plot
I'm trying to numerically integrate the equations of motion for a satellite moving about a spheroidal Earth using Heun's method, but I get a RuntimeWarning: invalid value encountered in scalar divide, ...
1
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1
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182
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FitzHugh–Nagumo model output not resembling what is shown on Wikipedia
First off, I just want to mention that I am a biology researcher not trained in differential equations or dynamical systems. I am doing this as an exercise to get a bit of intuitive understanding of ...
2
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1
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111
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1D Poisson equation in MATLAB
I'm solving Poisson equation and I've come across a problem that I cannot understand.
All methods I'm using give a different result than the algebraic solution, which I believe is correct. Everything ...
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1
answer
105
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How to python code a distributed delayed differential system in python?
Already tried with ddeint, does not yield good results. I have an equivalent PDE system that works just fine and I can compare results. The key of the problem is that the system is coupled, so I ...
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1
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176
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One adaptive-time-step solution for ODE
I want to solve some ODE just for one time step. The time step is decided internally by the solver, not by me. Is there a python adaptive-time-step ode solver which could do this? For illustration the ...
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0
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66
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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 ...
1
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2
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128
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graphing nonlinear systems of ODEs in python
the model Im trying to graph this model however I am just not sure whether my code is leading me to a reasonable solution:
import numpy as np
import matplotlib.pyplot as plt
from scipy.integrate ...
1
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2
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113
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deviation in solutions (differential equations) using odeint vs runge-kutta-4th
I am modelling a Coupled Spring-Mass-System: Two objects with masses m1 and m2, and are coupled through springs with spring constants k1 and k2, with damping d1 and d2.
Method 1: taking a cookbook-...
1
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1
answer
562
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Why is the accuracy of scipy.integrate.solve_ivp (RK45) extremely poor compared to my homemade RK4 implementation?
What I want to solve
I solved a system of ordinary differential equations using scipy.integrate.solve_ivp and compared the results with my homemade 4th-order Runge-Kutta (RK4) implementation.
...
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69
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Negative Eigenvalues of the Woods-Saxon Nuclear Potential for Oxygen ND Eigensystem
I am trying to use ND Eigensystem to find the eigenvalues of the Woods-Saxon Potential Schroedinger Equation for Oxygen. I've defined the potential and operator, but I know the functions given are ...
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56
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Matlab error solving symbolic systems of equations as functions of time
I have the following system of differential equations that arose form circuit analysis where the following simplification was made.
Simplification of equations
The systems of equations is as follows:
...
0
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1
answer
136
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Solving non-linear ODE system with boundary conditions in Python
I am trying to solve this system of differential equations:
The functions should behave like this, as r-> infinity (F = g = lambda = const.):
A while ago I had a similar problem and a user was ...
1
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0
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96
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Solving Nonlinear Boundary Value Problem with Constraints
I want to solve the following boundary value problem
where S, k_i, x_f, α_1, and θ are known parameters. We are trying to solve for h(x), p, and θ_d.
My idea was to use finite differences to create a ...
1
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1
answer
110
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Why does my planetary orbit simulation produce a straight line instead of an elliptical orbit?
I'm trying to simulate the orbit of a planet using the compute_orbit method, but when I plot the resulting positions, I get a straight line instead of an expected elliptical orbit. Below are the ...