At 07:28 18-06-96 -0700, you wrote: >Now for a math question. In analytical geometry the equation of an >ellipse is: (with the origin at the center and semi-axes a and b) > >(X**2/a**2) + (y**2/b**2) = 1 (**2 means squared) > >the equation of a hyperbola is: > >(X**2/a**2) - (y**2/b**2) = 1 > >Can we draw a sundial from these equations? How are a and b related to >latitude, declination of the sun, and hour angle? This will keep me off >the streets and out of trouble for a while. > >Sincerely, > >********************************************************************* >Warren Thom [EMAIL PROTECTED] or [EMAIL PROTECTED] >Hompage Still working on it. >********************************************************************* > Hi Warren,
A few questions .... Many replies..... Here is another one. As Luke J Coletti already replied it is normally not done using the classic formulas. I looked at this problem already, but it is a hell of a job to find the proper values for the parameter a and b. I am myself searching for the universal recipe using the general formula ax**2 + bxy + cy**2 + dx + ey + f = 0 which represent ALL conic sections by a flat surface, including all straight lines! I am trying to find the relations between the parameters a - f and the basic gnomonic items known. Ton van de Beld of the Dutch group of 'sundial freaks' (De Zonnewijzerkring) wrote already a report on it, but I still didnt have time to study it. The reason for my search is probably the same as yours: easier constructing and drawing the datelines. But also easier calculating on simple calculators and last but not least: the challenge. Good luck with your dial Thibaud Taudin-Chabot <[EMAIL PROTECTED]>
