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Show HN: Interactive Essay on Signals, Sampling and the Fourier Transform

jackschaedler.github.io

21–30 of 45 posts

Re: Show HN: Interactive Essay on Signals, Sampling and the Fourier Transform

#21
This is awesome. Congratulations! It should be thrown in the face of the textbook publishing industry that still charges $100+ dollars for yearly reprints of paper bricks.

This is what the textbooks should be in the 21st century! Outstanding work and hopefully it will inspire new generation of academics to take the outdated textbook publishing monopolies out of the loop in the future.

Re: Show HN: Interactive Essay on Signals, Sampling and the Fourier Transform

#22

Earlier quoted context omitted.

Thanks! Let me know if there are other topics you'd like covered, or areas that need more explanation.

This is great! I'd love to see sections on convolution, the Dirac delta function, and the continuous (possibly multi-dimensional) Fourier transform.

Seconded on convolution and the Dirac delta.

Re: Show HN: Interactive Essay on Signals, Sampling and the Fourier Transform

#25
It seems like the equation processing gets messed late in section 4 - $$ \mathrm{DFT}[k] = \sum_{n=0}^{N-1} \mathrm{x}[n] \cdot (cos(\varphi) - sin(\varphi)i) \\ where \quad \varphi = k \frac{n}{N} 2\pi $$

https://jackschaedler.github.io/circles-sines-signals/dft_wa...

there are a few other examples in section 5

Aside from that, this is really great.

Re: Show HN: Interactive Essay on Signals, Sampling and the Fourier Transform

#27

Earlier quoted context omitted.

Thanks! Let me know if there are other topics you'd like covered, or areas that need more explanation.

Another topic that has confounded me as much as FFTs are Quaternions.

I found this example by Steven Wittens to be remarkably well done: http://acko.net/blog/animate-your-way-to-glory-pt2/

See the section "Blowing up the Death Star" and note that there are 100 parts total.

"So that's quaternions, the magical rotation vectors."

Re: Show HN: Interactive Essay on Signals, Sampling and the Fourier Transform

#29
post #25

It seems like the equation processing gets messed late in section 4 - $$ \mathrm{DFT}[k] = \sum_{n=0}^{N-1} \mathrm{x}[n] \cdot (cos(\varphi) - sin(\varphi)i) \\ where \quad \varphi = k \frac{n}{N} 2\pi $$ https://jackschaedler.github.io/circles-sines-signals/dft_wa... there are a few other examples in section 5 Aside from that, this is really great.

That's because you're accessing the site from HTTPS, or you have HTTPS Everywhere installed which is doing it for you. I think he's loading MathJax as HTTP, which means it gets blocked because it's coming from an insecure connection.

Re: Show HN: Interactive Essay on Signals, Sampling and the Fourier Transform

#30
post #25

It seems like the equation processing gets messed late in section 4 - $$ \mathrm{DFT}[k] = \sum_{n=0}^{N-1} \mathrm{x}[n] \cdot (cos(\varphi) - sin(\varphi)i) \\ where \quad \varphi = k \frac{n}{N} 2\pi $$ https://jackschaedler.github.io/circles-sines-signals/dft_wa... there are a few other examples in section 5 Aside from that, this is really great.

That's because you're accessing the site from HTTPS, or you have HTTPS Everywhere installed which is doing it for you. I think he's loading MathJax as HTTP, which means it gets blocked because it's coming from an insecure connection.

Ah! Thank you so much.
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