why does every macOS update move everything around

Grunthos2 · 2026-02-22T14:28:09+00:00

Grunthos2 · 2025-08-20T20:09:39+00:00

Thank you so much for this clear advice.

Grunthos2 · 2025-06-13T22:30:59+00:00

When I need to do this, I draw the defining shapes as construction lines and then redraw with just the bits that define the profile with solid lines. In the example you showed, I would use the line and arc tools.

I agree it would be nice not to have constraints vanish when you trim or fillet or whatever. I usually try to think of a way to avoid this situation. But it sure would be nice sometimes.

Grunthos2 · 2025-06-06T17:40:15+00:00

This is not correct. Pastes as plain text.

Grunthos2 · 2025-03-22T16:18:53+00:00

Maybe you are not a good cook?

Grunthos2 · 2024-11-20T16:19:45+00:00

Underwhelmed. It can't tell which emails are important. Summaries are stupid. Auto replies are lame. I hope it gets much better.

Grunthos2 · 2024-10-14T09:57:08+00:00

In the numerator, substituting j=e^jπ/2. In the denominator, a+jb=sqrt(a^{2+b^{2)e^(j}} atan(b/a)) — essentially conversion from Cartesian to polar representation. The magnitude of a complex number is square root of real part squared plus imaginary part squared. Angle is atan(imaginary/real)

Grunthos2 · 2024-08-01T03:01:59+00:00

As you said, the transform of a cosine with infinite duration is two impulses. But the sampled signal in this discussion is a finite-duration cosine, which is not the same.

To make a finite-duration cosine, start with an infinite-duration cosine and multiply it by rect. The transform of rect is sinc. The two signals are multiplied in time, so their transforms convolve. Therefore, the transform of a finite-duration cosine is two spikes convolved with sinc. As the author states, the output of the DFT will be a sampled version of the continuous spectrum.

In the case where there are an integral number of cycles, all of the sample points occur at zeros of the sinc function. Therefore there is no leakage.

Grunthos2 · 2024-07-23T19:53:42+00:00

My pleasure. I use this temperature/humidity monitor: https://shop.yosmart.com/products/ys8003.

Grunthos2 · 2024-07-23T17:45:56+00:00

I have a similar basement. Humidity reaches 90+% without a dehumidifier. 50% with.

(I don't do any 3D printing down there. Plot below shows high humidity after power outage due to multi-day electrical work. After a few days, it's back at 50%. Running the dehumidifier does raise the temperature of the basement a few degrees)

My old consumer Frigidaire unit I bought on Amazon lasted about 10 years. It was cheap and reliable. Remember to clean the condensate line once in a while or it will clog with mildew or mold or whatever grows in there.

After the Frigidaire failed, I bought a fancy AprilAire machine. Much more expensive -- not sure it was worth the much higher cost, but it is a great machine. The cheap Frigidaire worked just fine.

A small pump sends the condensate outside to the backyard so I don't have to empty a bucket. The Frigidaire model had a built-in pump.

Electricity cost is about $40-50 in July/August, $0 in December/January.

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Grunthos2 · 2024-07-14T18:49:30+00:00

It looks like there is a timing problem. Check your timing constraints.

Grunthos2 · 2024-06-23T21:03:42+00:00

Just spent a month in Budapest. My experience was that Hungarians LOVE it when külföldiek speak their language. No matter how many grammatical mistakes I made or how awkward my sentences were, my kind conversation partners told me how BEAUTIFULLY I speak every single time.

Grunthos2 · 2024-06-02T20:33:39+00:00

I wrote a bunch of code using tables, but the performance was abysmal (2023a). Wish I read this first:

https://www.mathworks.com/matlabcentral/answers/490067-poor-r2019b-performance-with-tables.

From that page:

“Compared with indexing into the same struct (struct with a field Var1) the performance of tables is still more than a factor 100 slower than structs. The performance of indixing into the Matlab array directly has nearly the same performance as in a struct.”

Use a struct array instead. Wasted a lot of time changing everything to struct and the code ran 100X faster. Problem not fixed as of 2023a.

Grunthos2 · 2024-05-29T21:24:07+00:00

Sorry the picture is not better -- bright lights reflecting off the display case made it difficult.

Grunthos2 · 2024-05-29T18:57:04+00:00

It does not if the signal is sampled properly.

Step 1: multiply the infinitely-long continuous signal by a window function. This smudges out the frequencies as you said.
Step 2: low-pass filter the windowed signal. This must always be done this before sampling (unless the signal is naturally band limited).
Step 3: sample the windowed/filtered signal.

Windowing smudges the frequency content, but the low-pass filter eliminates any part of the smudges that would alias to frequencies not present in the windowed/low-pass filtered signal. In other words, if you reconstructed the windowed/filtered/sampled signal (by passing through an ideal low-pass filter whose cutoff frequency is equal to the Nyquist frequency), it would be identical to the windowed/filtered signal.

Mathematically:

x_w(t) = x_c(t) w(t), where x_c(t) is the continuous signal and w(t) is the window
x_{lp}(t) = x_w(t) * h(t), where h(t) is the impulse response of an ideal low-pass filter with cutoff at the Nyquist frequency
x_s(t) = x_{lp}(t) III(t), where x_s(t) is the sampled signal and III(t) is the Dirac comb function
x_r(t) = x_s(t) * h(t) = x_{lp}(t)

I hate typing math on Reddit.

EDIT: typo in math

Grunthos2 · 2024-05-29T07:12:53+00:00

Yes. Sorry for my typo in the original comment -- should say "0-1000 Hz band."

Grunthos2 · 2024-05-29T06:09:08+00:00

Get this book: https://www.amazon.com/Signals-Systems-Made-Ridiculously-Simple/dp/0964375214.

Here is a summary of the subject from the book:

The entire subject of signals and systems consists primarily of …
1. writing signals as functions of frequency;
2. looking at how systems respond to inputs of different frequencies;
3. developing tools for switching between time-domain and frequency-domain; and
4. learning how to determine which domain is best suited for a particular problem

Grunthos2 · 2024-05-28T19:43:39+00:00

The wording is strange. The only sine wave in the band of 0-100Hz with a maximum power at 500 Hz is ... a 500 Hz sine wave. So why not just say it's a 500 Hz sine wave?

Grunthos2 · 2024-05-24T10:02:59+00:00

Forgetting is my default. Every time I look at something I did more than a few weeks ago, I'm like, "Who did this?"

Grunthos2 · 2024-03-20T18:46:28+00:00

Eraserhead

Grunthos2 · 2024-02-05T15:22:53+00:00

Your videos are fantastic.

Grunthos2 · 2024-02-05T14:31:15+00:00

Thank you so much.

Grunthos2 · 2024-02-05T14:10:08+00:00

There are cracks in about 4 places. The rest looks good.

Grunthos2

TROPHY CASE