Frequently Asked Questions
Where did your glyphs come from?
All of the graphics in Maya Date were created specifically for this program. The glyphs are all based on the Mayan forms as recorded in historical records and monuments. We stayed true to the basic graphical elements of each glyph, but like the Mayans themselves we interpreted some of the details. Our goal was to make these images look beautiful on the iPhone's display. Every glyph was hand-tuned until it looked great.
There are other sets of Mayan glyphs available on the web, although most represent a signficiant amount of work by the author and must be licensed for commercial use. Probably the easiest way to get Mayan glyphs for any use, including commercial applications, is to download the freeware Mayan.ttf font, available on many font repositories. There are also three Mayan fonts available from Ecological Linguistics for non-commercial use only: daysbold.ttf, dayscodicile.ttf, and tun.ttf. For all of these fonts, you'll have to do some digging to figure out which glyphs you'll need for any particular use.
Why are some results different from other Mayan calendar programs?
Calendars can be tricky things to program correctly. Many programmers quite sensibly rely on the built-in calendar software that's supplied with each computer's operating system, or the browser's plugin programs, rather than write their own date-keeping software. In general this is a fine idea, since we expect that kind of system software to be accurate, dependable, and fast.
Unfortunately, it's not always simple to run a calendar backwards, as we must do with the Gregorian calendar when computing dates prior to its introduction in 1584. Different programmers can decide to implement the process in different ways, leading to different answers. For example, some programmers add or remove days to compensate for 10 days in October 1584 that were "removed" by decree. Others forget that the Gregorian calendar has no Year 0, but goes from -1 BC directly to 1 AD. Due to these kinds of issues, and others, the very same program can be run on two different systems and produce two different dates. And these disagreements can accumulate as you go further into the past or future.
Even worse, some system's underlying calendars have bugs. If you stick to dates within a century or two of 2000 AD you'll usually get accurate values, but if you start to work with dates much farther in the past or future you can find that the results start to drift by days, weeks, or even years.
Sadly, the calendar software on the iPhone is not immune to these problems. Prior to 1584, the dates delivered by Apple's calendar start to drift by over a year (to see this for yourself, go to the Contacts book and set a birthday for a friend sometime in early 1500's or before; the date you've chosen with the spinning wheels will not match the date that's displayed above them). Thus all programs that rely on Apple's built-in calendar software will also calcluate Dates incorrectly, and this includes many of the Mayan calendars sold in the iTunes store.
To avoid these programs, the Maya Date application does not rely on any system software for calculating dates. It uses a new, carefully-designed algorithm to convert all Gregorian and Long Count dates into a custom internal format, and from that format back into dates. This calendar system has been exhaustively checked for accuracy over dates spanning several millenia. As a result, the calendar computations from Maya Date are accurate and reliable.
What's up with limits on the correlation constant?
Maya Date uses a custom calendar system to perform accurate date calculations (see the above question). That format imposes some technical limits on the range of the correlation constant, so that it may not go below 200,000 or above 1,000,000.