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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@aeva @dotstdy @jon_valdes start a new genre "deca-dance"
@demofox @dotstdy @jon_valdes well so far I can't tell the difference by ear between the soft sin and the double precision sin that clang gives me
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@demofox @dotstdy @jon_valdes well so far I can't tell the difference by ear between the soft sin and the double precision sin that clang gives me
@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
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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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Gli ultimi otto messaggi ricevuti dalla Federazione
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Global sumud flotilla: le barche italiane lasciano la costa siciliana alla volta di gaza, “buon vento”
@anarchia
Sono salpate, alla volta di Gaza, le imbarcazioni italiane della Global Sumud Flotilla dal porto siciliano di Augusta. Sono 18 le barche al momento, partite dalle coste siciliane questo sabato 13 settembre, che si uniranno in mare https://www.rivoluzioneanarchica.it/global-sumud-flotilla-le-barche-italiane-lasciano-la-costa-siciliana-alla-volta-di-gaza-buon-vento/
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@aeva "We shall put this river in a box and then everything's fine!"
Cue decades of flooding.
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@ataylor nothing a liberal application of hubris can't pretend to fix
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@aeva I mean, we already see similar issues with geographic borders. Especially rivers, because rivers really don't like to stay put.
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it's a good thing countries are pretty short lived geologically speaking otherwise plate tectonics would cause a lot of problems
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@kevingranade they did eventually redefine the kilogram as something other than robespierre's evaporating left nut at least
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@luana I figure the smaller the city the lower the odds you end up with grosstopically overlapping structures, legally speaking
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@aeva at least all the measurement units are nailed down.
https://www.nist.gov/pml/us-surveyfoot
Well, ok it could be worse.
