Need help calculating equation of time
Hello! At https://gist.github.com/1278755 - is anybody able to tell what's wrong with my equation of time calculation? Thank you! --Dwayne --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Approximating solar coordinates
Ricardo, I'm not sure what you mean, but here's my program: https://gist.github.com/1278755 I've managed to identify all the numbers (hopefully), but the calculation itself is not yet correct. --Dwayne On Wed, Oct 19, 2011 at 6:48 PM, Ricardo Cernic rncer...@uol.com.br wrote: Hi Dwayne, It has been a long time ago when I wrote my last program, but as far as I remember you usually can define the precision of a variable (int, long or float, double). Have you consider it? Usually these kind of calculation use / generate huge numbers. BR, Ricardo São Paulo - Brazil http://relogiosdesol.blogspot.com On 18/10/2011, at 16:48, Dwayne Henderson wrote: Oh, about the unladen swallow thing. I'm not sure if the dude who told me to put that there was just joking: http://www.youtube.com/watch?v=y2R3FvS4xr4 --Dwayne On Tue, Oct 18, 2011 at 8:28 PM, Dwayne Henderson its.code.in.h...@gmail.com wrote: Thanks a lot Andrew! I worked in your numbers. The calculation is still a bit off though: 1) Failure: test_equation_of_time(TestSolarCalculations): Expected 2011-10-01 10:23:00 UTC, not 2011-01-06 01:08:11 UTC. 2) Failure: test_suns_declination(TestSolarCalculations): Expected -3.18, not -3.2087920449753007. If you have any thoughts about that, or any more suggestions, please let me know. https://gist.github.com/1278755 Thanks again man. --Dwayne On Tue, Oct 18, 2011 at 4:46 PM, Andrew James andrew.ja...@securetogether.co.uk wrote: Dwayne I’ll let others who know more comment further, but the link you have found names some of the numbers from which their meaning should be clearer (?), though I don’t think the name for 0.020 is at all helpful ... Also 360 / 0.98560028 = 365.259636 = anomalistic year in days 360 / 0.98564736 = 365.2421897 = mean tropical year in days So the numbers 0.98560028 and 0.98564736 convert days to fractions of one of those kinds of years in degrees. 0.00014 is more or less half of 0.01671 squared which I think comes from the approximation to an ellipse by periodic terms. Hope this is some help. Andrew James From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Dwayne Henderson Sent: 12 October 2011 12:30 To: sundial@uni-koeln.de Subject: Approximating solar coordinates Greetings! At the U.S. Naval Observatory's algorithm for calculating solar coordinates - would anybody happen to know what the numbers 357.529, 280.459, 0.98560028, 0.98564736, 1.915, 0.020, 1.00014, 0.01671, 0.00014, 23.439 and 0.0036 represent? I've done all the Googling I can, but this is the closest I've gotten: https://gist.github.com/1278755 Much obliged! --Dwayne This message has been scanned for viruses by MailControl. Secure Meters (UK) Ltd. is a registered company in England: 2199653 Secure House, Moorside Road, Winchester, SO23 7RX This correspondence is confidential and solely for the intended recipient(s). If you are not the intended recipient, you must not use, disclose, copy, distribute or retain this message or any part of it. If you are not the intended recipient please delete this correspondence from your system and notify the sender immediately. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Approximating solar coordinates
Greetings! At the U.S. Naval Observatory's algorithm for calculating solar coordinateshttp://aa.usno.navy.mil/faq/docs/SunApprox.php- would anybody happen to know what the numbers 357.529, 280.459, 0.98560028, 0.98564736, 1.915, 0.020, 1.00014, 0.01671, 0.00014, 23.439 and 0.0036 represent? I've done all the Googling I can, but this is the closest I've gotten: https://gist.github.com/1278755 Much obliged! --Dwayne --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Approximating solar coordinates
Oh, about the unladen swallow thing. I'm not sure if the dude who told me to put that there was just joking: http://www.youtube.com/watch?v=y2R3FvS4xr4 --Dwayne On Tue, Oct 18, 2011 at 8:28 PM, Dwayne Henderson its.code.in.h...@gmail.com wrote: Thanks a lot Andrew! I worked in your numbers. The calculation is still a bit off though: 1) Failure: test_equation_of_time(TestSolarCalculations): Expected 2011-10-01 10:23:00 UTC, not 2011-01-06 01:08:11 UTC. 2) Failure: test_suns_declination(TestSolarCalculations): Expected -3.18, not -3.2087920449753007. If you have any thoughts about that, or any more suggestions, please let me know. https://gist.github.com/1278755 Thanks again man. --Dwayne On Tue, Oct 18, 2011 at 4:46 PM, Andrew James andrew.ja...@securetogether.co.uk wrote: Dwayne ** ** I’ll let others who know more comment further, but the link you have found names some of the numbers from which their meaning should be clearer (?), though I don’t think the name for 0.020 is at all helpful ... ** ** Also 360 / 0.98560028 = 365.259636 = anomalistic year in days 360 / 0.98564736 = 365.2421897 = mean tropical year in days ** ** So the numbers 0.98560028 and 0.98564736 convert days to fractions of one of those kinds of years in degrees. ** ** 0.00014 is more or less half of 0.01671 squared which I *think* comes from the approximation to an ellipse by periodic terms. ** ** Hope this is some help. ** ** Andrew James ** ** -- *From:* sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] *On Behalf Of *Dwayne Henderson *Sent:* 12 October 2011 12:30 *To:* sundial@uni-koeln.de *Subject:* Approximating solar coordinates ** ** Greetings! At the U.S. Naval Observatory's algorithm for calculating solar coordinates http://aa.usno.navy.mil/faq/docs/SunApprox.php - would anybody happen to know what the numbers 357.529, 280.459, 0.98560028, 0.98564736, 1.915, 0.020, 1.00014, 0.01671, 0.00014, 23.439 and 0.0036 represent? I've done all the Googling I can, but this is the closest I've gotten: https://gist.github.com/1278755 Much obliged! --Dwayne This message has been scanned for viruses by MailControlhttp://www.mailcontrol.com/ . *Secure Meters (UK) Ltd. is a registered company in England: 2199653* Secure House, **Moorside Road, Winchester**, **SO23 7RX This correspondence is confidential and solely for the intended recipient(s). If you are not the intended recipient, you must not use, disclose, copy, distribute or retain this message or any part of it. If you are not the intended recipient please delete this correspondence from your system and notify the sender immediately.** --- https://lists.uni-koeln.de/mailman/listinfo/sundial
