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Questions tagged [numpy]

NumPy is the fundamental package for scientific computing with Python.

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1 answer
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Python Finite Difference Schemes for 1D Heat Equation: How to express for loop using numpy expression

Hello all, I've recently been introduced to Python and Numpy, and am still a beginner in applying it for numerical methods. I've been performing simple 1D diffusion computations. I suppose my ...
Leonardo Parra García's user avatar
13 votes
3 answers
2k views

How to express this complicated expression using numpy slices

I wish to implement the following expression in Python: $$ x_i = \sum_{j=1}^{i-1}k_{i-j,j}a_{i-j}a_j, $$ where $x$ and $y$ are numpy arrays of size $n$, and $k$ is a numpy array of size $n\times n$. ...
N. Virgo's user avatar
  • 1,203
9 votes
2 answers
897 views

Continuity of eigenvectors of parametric matrix

I have $n$-dimensional matrices $\mathrm{\hat{H}}(\vec{k})$ depending on vector parameter $\vec{k}$. Now, eigenvalue routines return eigenvalues in no particular order (they are usually sorted), but ...
tomic's user avatar
  • 91
5 votes
1 answer
3k views

Logistic regression with Python

I am trying to code up logistic regression in Python using the SciPy fmin_bfgs function, but am running into some issues. I wrote functions for the logistic (...
tchakravarty's user avatar
4 votes
1 answer
557 views

Going to try to move some of my scipy/numpy calculation to a new GPU, how to avoid disappointing results?

update: I've refactored the question based on helpful advice in the linked meta. I'm a heavy user of Python's NumPy and SciPy (and not much else) and for years I could run anything I need on my laptop....
uhoh's user avatar
  • 1,048
4 votes
0 answers
177 views

How amenable is this 2D Frenkel–Kontorova-like energy minimization problem in Python to the use of a modest PC + GPU? (Heavy reliance on indexing)

@Richard's answer to Going to try to move some of my scipy/numpy calculation to a new GPU, how to avoid disappointing results? is quite helpful, and as promised I've added a simple running example ...
uhoh's user avatar
  • 1,048
3 votes
1 answer
1k views

My calculated laser pulse duration is too large. Where am I wrong?

I am currently writing a small Python script to estimate the pulse duration from the optical spectrum. At the end, the idea is to observe the effects of the spectral phase on the pulse duration and ...
Adrien's user avatar
  • 31
1 vote
2 answers
1k views

Numpy FFT gives me a pulse shorter than it should be. Not sure what I am doing wrong

I've created a code (Python, numpy) that defines an ultrashort laser pulse in the frequency domain (pulse duration should be 4 fs), but when I perform the Fourier Transform using DFT, my pulse in the ...
python_enthusiast's user avatar
1 vote
0 answers
304 views

Calculate integrals using numpy.fft

Good evening, I would like to understand why I do not get the correct result: I assume that I know my function on discrete data points and expand it as a discrete Fourier transform: $\text{sin}(x)=\...
reloh100's user avatar
  • 153
0 votes
1 answer
919 views

roots of polynomials of high degree: LinAlgError: Eigenvalues did not converge

I wrote a simple script to generate random polynoimals $\displaystyle f(z)= \sum_{k=0}^N a_k \frac{z^k}{\sqrt{k!}} $ of high degree and find their roots. For more discussion on random polyomials see ...
john mangual's user avatar
0 votes
2 answers
783 views

Is it possible to partition 2D data into bins such that each bin contains the same number of samples?

I am trying to sort data following a bivariate distribution into a numpy histogramdd, where each bin should contain the same number of data points (to the nearest whole sample). I expect that some ...
Zac's user avatar
  • 127