i nerd sniped myself tonight and i imagine the NSA operative who is assigned to me is very confused by the increasingly erratic and frustrated google searches for HOW DO I CALCULATE THE MOON WHERE IS THE MOON
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@demofox @dotstdy @jon_valdes assuming I didn't screw anything up adapting Jon's shader toy, the 30 iteration soft sin also has the surprising property of being able to clip out of the expected -1.0 to 1.0 output range https://github.com/Aeva/mollytime/blob/af58e9237903856b6193a116ae6408038dc47d4a/src/patch.cpp#L319
@aeva @demofox @dotstdy @jon_valdes There's lots of versions of CPU sin/cos as well. The fastest is basically identical to the GPU one - about 12 bits of precision, IIRC. Then they do iteration internally if you want higher precision. There's no magic - everything costs!
As you noticed, sometimes it's better not to call sin-vs-cos, because you're not guaranteed to get magnitude 1.0. In those cases it's better to get sin and derive the other by doing sqrt(1-sin^2).
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@aeva @demofox @dotstdy @jon_valdes There's lots of versions of CPU sin/cos as well. The fastest is basically identical to the GPU one - about 12 bits of precision, IIRC. Then they do iteration internally if you want higher precision. There's no magic - everything costs!
As you noticed, sometimes it's better not to call sin-vs-cos, because you're not guaranteed to get magnitude 1.0. In those cases it's better to get sin and derive the other by doing sqrt(1-sin^2).
@aeva @demofox @dotstdy @jon_valdes Also, if you care about precision at all, do range reduction yourself beforehand. Otherwise you have no idea how it's being done internally.
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@aeva @demofox @dotstdy @jon_valdes Also, if you care about precision at all, do range reduction yourself beforehand. Otherwise you have no idea how it's being done internally.
@TomF @demofox @dotstdy @jon_valdes I already do the range reduction. I learned that the hard way once upon a time XD
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wikipedia: even the ancient babylonians knew how to use math to figure out what the moon is up to
me: great how do i do that
wikipedia: 😏
today's extremely basic astronomy question that i'm finding surprisingly difficult to find an answer to: are geographic coordinates and equatorial coordinates the same coordinate system except one is for looking up and the other is for looking down, or is there some essential conversion step needed to correlate them?
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today's extremely basic astronomy question that i'm finding surprisingly difficult to find an answer to: are geographic coordinates and equatorial coordinates the same coordinate system except one is for looking up and the other is for looking down, or is there some essential conversion step needed to correlate them?
i feel like i'm so close to getting this working. i found a simple implementation of ELP2000-85 that gives the approximate ecliptic coordinates and distance of the moon for a given julian century, i found math for translating between ecliptic and equatorial coordinates, and the math for working with the julian calendar looks easy enough, so i just need to figure out the missing conversions and decide on an internal time keeping standard
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i feel like i'm so close to getting this working. i found a simple implementation of ELP2000-85 that gives the approximate ecliptic coordinates and distance of the moon for a given julian century, i found math for translating between ecliptic and equatorial coordinates, and the math for working with the julian calendar looks easy enough, so i just need to figure out the missing conversions and decide on an internal time keeping standard
i think astronomy would be a lot simpler if ancient peoples didn't get so hung up on conceptualizing celestial bodies as spheres and simply invented linear algebra first
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i think astronomy would be a lot simpler if ancient peoples didn't get so hung up on conceptualizing celestial bodies as spheres and simply invented linear algebra first
@aeva On cosmology sequence breaks: Terence Tao noted that an ancient Greek heliocentrist got his arguments shot down because others said, hey, if the earth moves so much yet the stars seem to stay still, the universe would have to be *thousands* of times bigger than anyone figures it is. And how would you know, back then, it was way *more* than thousands of times bigger?
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i think astronomy would be a lot simpler if ancient peoples didn't get so hung up on conceptualizing celestial bodies as spheres and simply invented linear algebra first
@aeva a lot of things would be simpler if cults based on "perfect" shapes hadn't done all the [gestures] that they did
divine geometry is a helluva drug
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@aeva On cosmology sequence breaks: Terence Tao noted that an ancient Greek heliocentrist got his arguments shot down because others said, hey, if the earth moves so much yet the stars seem to stay still, the universe would have to be *thousands* of times bigger than anyone figures it is. And how would you know, back then, it was way *more* than thousands of times bigger?
@rf they were so close lol
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@aeva a lot of things would be simpler if cults based on "perfect" shapes hadn't done all the [gestures] that they did
divine geometry is a helluva drug
@aeva on the other hand getting extremely horny for triangles is both funny and kinda relatable, so
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@aeva a lot of things would be simpler if cults based on "perfect" shapes hadn't done all the [gestures] that they did
divine geometry is a helluva drug
@SnoopJ we're still using spherical trig in astronomy today despite earth being an ellipsoid
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@aeva on the other hand getting extremely horny for triangles is both funny and kinda relatable, so
@SnoopJ mood
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@SnoopJ we're still using spherical trig in astronomy today despite earth being an ellipsoid
@aeva well, yea, because astronomy doesn't really give a shit what shape the earth is anyway
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@aeva well, yea, because astronomy doesn't really give a shit what shape the earth is anyway
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I just want to calculate the current direction of tidal force from the observer's earth-relative position in space and time is that so wrong
@aeva oh what a fun one
have you encountered the thing where every computation in astronomy is coordinate conversion
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@aeva oh what a fun one
have you encountered the thing where every computation in astronomy is coordinate conversion
@ireneista yes
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@ireneista yes
@aeva "fun", isn't it
Gli ultimi otto messaggi ricevuti dalla Federazione
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now that I'm a bit further down this rabbit hole I'm realizing this isn't much different from the terrestrial cartography I did one summer in college about 16 years ago, except that your benchmarks are all moving a lot faster
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@ok That's what I thought.
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Bot server is here: https://github.com/evanp/activitypub-bot and you can ask @ok if they are OK
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The update was hard; the jsonld.js library was choking on the FEP's context document because Codeberg Pages, where FEP context documents are hosted, is unreliable.
I ended up adding a feature to the `activitystrea.ms` NodeJS library to let you pre-cache a context document, so it didn't have to go fetch it at run time. While I was under the hood, I also fixed a couple of bugs that made it hard to work with extra context documents.
The bot server is now working; I'm going to add more contexts.
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I updated the #ActivityPubBot server software to use FEP-5711, the inverse properties FEP. It is a way to declare two-way relations; if X has an `inbox` property with value Y, then Y has an `inboxOf` property with value X. It helps with navigation when you're using the ActivityPub API, and it also helps with spoofing (since both objects agree on the relationship).
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@lkngrrr are you on the plane right now?
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I know I am flying Air France to Paris in an Airbus 350 but WOW I was not prepared for how French this was gonna be
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Contro il ponte, contro la repressione! Solidarietà agli arrestati No Ponte (con gli indirizzi per scrivere ai compagni e indicazioni per il sostegno economico)
@anarchia
Riceviamo e diffondiamo: CONTRO IL PONTE, CONTRO LA REPRESSIONE SOLIDARIETÀ AD ANDRE, BAK E GUI Negli scorsi giorni trehttps://www.rivoluzioneanarchica.it/contro-il-ponte-contro-la-repressione-solidarieta-agli-arrestati-no-ponte-con-gli-indirizzi-per-scrivere-ai-compagni-e-indicazioni-per-il-sostegno-economico/
