Feedback about Warm-up: numpy - on the Polynomial (Mis)Fit Example in the Tensors Tutorial

[camargocr]

Hi there,

I was looking at the tutorial on fitting a polynomial with NumPy and PyTorch:
https://docs.pytorch.org/tutorials/beginner/examples_tensor/polynomial_numpy.html

I noticed that the resulting third-degree polynomial is not a very good fit for the sin(x) function it's supposed to approximate:
f(x) = 0.0003655185795843861 + 0.8513230793867113 x + -6.305803723372667e-05 x² + -0.09255975933441395 x³

You can see a graph of both functions here—they look pretty different:
https://www.geogebra.org/calculator/qyykjrjf

My concern is that this might be a confusing example for beginners. It could give them the wrong impression of what a good result looks like when using PyTorch.

Cheers,
Carlos Rogério Camargo

cc @albanD @jbschlosser