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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/MIAF7FIPQGSN2LHUG6ZC4A2X3EHSZZA3/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "MIAF7FIPQGSN2LHUG6ZC4A2X3EHSZZA3",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/4YAQ6WJ52QA46R3IFNDAGYUYTF4CMT3I/?format=api",
    "sender": {
        "address": "ve9qrp (a) gmail.com",
        "mailman_id": "4d6061838db34aba9a1c4722addebfaf",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/4d6061838db34aba9a1c4722addebfaf/emails/?format=api"
    },
    "sender_name": "Bruce Robertson",
    "subject": "[amsat-bb] Re: use of PI in amsat development practice",
    "date": "2010-03-14T19:24:46Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/4YAQ6WJ52QA46R3IFNDAGYUYTF4CMT3I/?format=api",
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        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/MC7WK2FMNEMKRGEYNMIVLJHR7ZKFLERD/?format=api",
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/BGVMUTYJGUKKYHBJHE2MDMFDD52CPOUA/?format=api"
    ],
    "votes": {
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        "status": "neutral"
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    "content": "On Sun, Mar 14, 2010 at 1:22 PM, Samudra Haque <[email protected]> wrote:\n> Hi, Pi-Day is today (3/14/2010) also we just sprang forward by 1 hour.\n> (http://www.cnn.com/2010/TECH/03/12/pi.day.math/index.html?hpt=C2) and\n> apparently it's also Einsteins Birthday!\n> (http://en.wikipedia.org/wiki/Albert_Einstein)\n>\n> Wow a lot of key dates here.\n>\n> My question is: in amateur satellite design/planning how many\n> significant digits are used to calculate the value of pi? Is there a\n> significant difference in results between (4 decimal poinits) and (3\n> decimal points).\n\nWhat an interesting question! As many of you know, I'm having fun\nporting the G3RUH's Plan13 algorithm to the Atmel platform. One of the\nfirst things you want to be able to do in programs like this is to\nconvert degrees to radians; and that means pi.\n\nIn the appropriate header pi is defined thus:\n#define M_PI 3.141592653589793238462643\nBut I use 4-bit precision floating values. (This platform *can* use\n8-bit, but because it is Harvard architecture, I come pretty close to\nkilling my stack if I do 8-bit math with the 2kB SRAM.)\nWith this ruby oneliner, I can see the resulting bytes:\n>> [3.141592653589793238462643]].pack(\"f\").each_byte {|c| print c.to_s(16), ' '}\ndb f 49 40\n(This is using the ruby command-line interpreter 'irb').\nBy paring off numbers from the end, I can see that the my code is\nactually using roughly the following decimal value:\n3.14159265\n\nThe resulting accuracy can be attested in this (previously posted)\nvideo, beginning at about 1:30\nhttp://www.youtube.com/user/VE9QRP#p/a/u/0/TP_fq_frqKw\n\nHere's something people might not know about the letter pi. It is\nclosely related in ancient Greek to the letter 'phi'. While, we (at\nleast the Western European 'we') pronounce phi as an 'ffff', in\nancient Greek it was a 'p' sound with a bit of a puff of air after it,\n'p' + 'huh'. There was a similar relationship in Greek between kappa\nand chi.\n\n73, Bruce\n\n-- \nhttp://ve9qrp.blogspot.com\n\n\n> In professional space missions, such as NASA, what is the practice\n> with regards to use of Pi ? Are there any published standards?\n>\n> Using Excel, is there any way to generate a large range of pi ?\n>\n> -samudra N3RDX\n> _______________________________________________\n> Sent via [email protected]. Opinions expressed are those of the author.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n>\n",
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}