Deriving Spectral Features in 3D with NumPy and RFFT

Here’s the Key Insight 观点提炼 for the video about "Spectral Derivative in 3D using NumPy and the RFFT":

"Alright, buckle up for a trip through the mind-bending world of 3D spectral derivatives! 🌀🔮 We’re diving deep into FFT magic to tease out those gradients, all in the cozy comfort of NumPy. 🧙✨ With a sprinkle of Plotly for visualization flair, we’re slicing, dicing, and rotating functions like a wizard with a wand. 🪄✨ Just remember, when the FFTs align and the gradients dance, we unveil the hidden truths of our 3D fields. 💃🕺 Let’s ride this wave of spectral insight and transform the mundane into the mind-blowing!"

Done in 47 words! 🎉

Introduction

In this video, we delve into the n-dimensional fast Fourier transformation to take spectral derivatives of a 3D field using NumPy and the RFFT. If you’re interested in joining the PastorLabs team, they’re currently hiring for software positions – check out PastorLabs Careers for details.

Defining the Domain 🌐

Let’s begin by defining the domain. In our case, it’s a unit cube in three dimensions with an extent of one in each direction. We discretize each dimension with 40 points. This allows us to create a mesh, leveraging NumPy for efficient operations.


| Dimension   | Points |
|-------------|--------|
| X Direction |   40   |
| Y Direction |   40   |
| Z Direction |   40   |

Function Definition 📊

Now, let’s define the function we want to differentiate. It’s a collection of modes in X, Y, and Z directions. The function is a scalar field, and we’re interested in its gradient, represented by partial derivatives.

**Function F:**
\[ f(\mathbf{x}) = \cos\left(2\pi \frac{x_0}{L}\right) \sin\left(2\pi \frac{x_1}{L}\right) \cos\left(2\pi \frac{x_2}{L}\right) \]

Visualization 📈

Before delving into spectral derivatives, let’s visualize the original function and its partial derivatives using Plotly. We employ a custom function for rendering 3D volume plots with subplots for each field.

Spectral Derivatives 🚗

Now, onto the main task – calculating the spectral derivatives. We create wave number meshes, derive the function, and visualize the results. The spectral derivative aligns well with the analytical derivative, confirming the accuracy.

Conclusion 🎉

In conclusion, we’ve explored taking spectral derivatives in 3D using NumPy and the RFFT. This technique proves powerful for analyzing functions with complex behavior. For more insights into machine learning and simulation intelligence, check out PastorLabs.

Key Takeaways 🚨

  • Spectral derivatives provide precise insights into function behavior.
  • NumPy and RFFT offer efficient tools for these computations.
  • Visualization plays a crucial role in understanding complex data.

Feel free to explore the provided Notebook for a hands-on experience. If you enjoyed this video, consider supporting the creator on Patreon. Stay tuned for more fascinating explorations in mathematical topics!

About the Author

Machine Learning & Simulation
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About the Channel:

Explaining topics of 🤖 Machine Learning & 🌊 Simulation with intuition, visualization and code.——Hey,welcome to my channel of explanatory videos for Machine Learning & Simulation. I cover topics from Probabilistic Machine Learning, High-Performance Computing, Continuum Mechanics, Numerical Analysis, Computational Fluid Dynamics, Automatic Differentiation and Adjoint Methods. Many videos include hands-on coding parts in Python, Julia, or C++. The videos also showcase the application of the topics in modern libraries like JAX, TensorFlow Probability, NumPy, SciPy, FEniCS, PETSc and many more.All material is also available on the GitHub Repo of the channel: https://github.com/Ceyron/machine-learning-and-simulationEnjoy :) And please leave feedback.If you liked the videos, feel free to support the channel on Patreon: https://www.patreon.com/MLsimIf you want to make a one-time donation, you can do so via PayPal: https://paypal.me/FelixMKoehler
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