All Questions
414 questions
0
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35
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Jacobi method converges faster than Gauss-Seidel in case of Laplace equation
It is need to solve the problem using the Jacobi method: d^T/dx^2 + d^2T/dy^2 = 0 with conditions at the boundaries of the square:
T(0, y) = 1, T(x, 1) = 1, dT/dx(1, y) = 1 - y, dT/dy(x, 0) = x.
...
0
votes
1
answer
73
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polynomial evaluation producing non-differentiable behavior in Python
I'm trying to evaluate a polynomial of degree 61. However, around the point sqrt(2) I get some weird behavior. The graph of the polynomial becomes erratic. What could be the reason for this. The ...
- 113
1
vote
1
answer
47
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Unexplained gain in my code when solving coupled differential equations using solve_ivp() in python
I am trying to solve two coupled differential equations in python using the solve:ivp() function from scipy.integrate but I get an unexplained gain on one of my terms that breaks the equation. It is ...
0
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0
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35
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Optimizing a numerical integration that involves matrices using sympy
The expression I'm integrating is
Where the latent variables are sampled from the a multivariate distribution as following:
And the random variables w_n given a latent variable is sampled from a ...
- 71
1
vote
2
answers
81
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Simple 1 D dispersion equation numerical solution
I am new to coding and trying to solve a simple 1D dispersion equation.
The equation and boundary conditions:
adC/dx = bd^2C/dx^2
x = hj, C = C0; x = - inf, C =0
The analytical solution is
C = C0 * ...
- 13
2
votes
1
answer
86
views
How can I approximate 255/sqrt(x) using Newton's method?
I am trying to approximate 255 / sqrt(x) using Newton's method to avoid using division or the sqrt() operation on an architecture where those operations are expensive.
My derivation is:
y = 255 / sqrt(...
1
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0
answers
56
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How to efficiently integrate over a hexagonal region using Cubature in python?
I need to integrate a two-variable function numerically using the Cubature package in Python. The two-dimensional region over which I want to integrate is a hexagon. Integrating it in a circular ...
1
vote
2
answers
205
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vectorize an Ax=b solver
A lot of numerical solvers (such as this one), for some reason, only supports solving Ax=b where x, b are vectors.
What if I want to solve AX = B, where X and B are matrices.
I know numerically one ...
- 231
0
votes
1
answer
103
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How to evaluating solutions to Coupled Nonlinear Elliptic ODEs with Relaxation Method?
I would like to determine the following system of coupled, nonlinear, elliptic ODEs of second order with boundary conditions f(0) = h(0) = 0, f(1) = h(1) = 1.
I used a relaxation method to solve the ...
- 49
0
votes
3
answers
108
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running sum of np.array with widely varying elements
I need to calculate the running sum of np.array. Let's say a is a given np.array of length l and n is an integer step, then I need an array b of length l - n + 1, where
b= [a[0]+a[1]+...+a[n-1], a[1]+...
- 19
2
votes
1
answer
539
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Solving coupled 2nd order ODE, numerical in Python
I would like to solve the following DGL system numerically in python:
The procedure should be the same as always. I have 2 coupled differential equations of the 2nd order and I use the substitution g'...
- 49
2
votes
1
answer
60
views
Problems to solve non-linear coupled dgl in python (numerical)
I have the following problem. I would like to solve the following DGL system numerically in python:
$$
\begin{align*}
&g'' + \frac{2}{r} g' - \frac{2}{r^2} g - \frac{3}{r} e g^2 - e^2 g^3 - \frac{...
- 49
0
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0
answers
35
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Custom Riemann solver
I have written my own Riemann solver for a specific problem.
Unfortunately, I am unable to update the solution over time and create a simulation using PyClaw. I am quite new to PyClaw and have tried ...
0
votes
0
answers
71
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Apply Crank-Nicolson method to wave equation with np.linalg.solve
I want to solve a system of equations, where x,y are the vectors which I want the solutions. And c,d are the solutions. A,B are matrix
x-y=c+d
y-Ax=Bd+c
The full problem which I tried to summarize ...
-1
votes
1
answer
593
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using pandas to number and coerce to force values to ints and still not working
Confused when I am trying to coerce dataframe to numeric. It appears to work when I look at structure but then I still get errors:
TypeError: unsupported operand type(s) for +: 'int' and 'str'
Code:
...
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