It is some time ago, that I was fighting with that model and how
to estimate the 3 parameters (until recognizing that one may want
restrictions for them).
Essentially one uses the statistics of the underlying data to get
a reasonable starting guess. 
For an estimation then one can use the Optimization package.
The gradients involved are best coded as a floating point library,
which here is done through a DLL (it should work on all Windows OS),
code in C is included for that.
Meanwhile all can be done using 'Compiler:-compile' or the Watcom
compiler delivered with Maple.
I left that older sheet as it is - in Maple 9 (may be one should
brush it up for concurrent Maple versions, they are grumbling a bit
about the code) and hope it is of interest despite of that.

Maple sheet: www.mapleprimes.com/files/102_Garch.mws
DLL + code:  www.mapleprimes.com/files/102_Garch.dll.zip
as a pdf:    www.mapleprimes.com/files/102_Garch.mws.pdf

We’re now at an inflection point in which symbolic technology will automate physical modeling and equation generation through tools like MapleSim. As a recent webinar hosted by Maplesoft and the Society of Automotive Engineers proved, engineers are fascinated by the application of the technology, and the technology itself.

Well, we've officially joined the web 2.0 revolution :) ... Maplesoft now has a page on Facebook.Come check it out and become a fan!

The Facebook page is intended to be a place for our “fans” to gather, share ideas and talk about their Maple experiences. The page will continue to be updated with interesting photos, videos (including a great one of some of our staff trying to work off the Christmas weight gain!...

• Voting patterns in Mexico and Florida.
• The size of files in your Maple 12 installation
• Stock trading volumes on the NYSE

What do all of these have in common? They, and other data sets drawn from the real world, often follow a non-intuitive pattern called Benford’s Law.

Maple 12.02 is now available. The Maple 12.02 update includes enhancements in a variety of areas, including:

Reduce became free and is available for download.

Alec

I have two suggestions how the developers of Maple could improve the software

1) Improved  capabilities for algebra.

Currently it is difficult to do mathematical manipulation (sometime even simple stuff) with Maple.

In a perfect world I could just right click on an expression and then get all the possible permutations of that expression.

I usually dont use Maple when it comes to manipulating algebraic expressions because I usually end up getting angry.

2) Loop protection

An annoying feature of Maple is that if it crashes (all too often) & you have not given your worksheet a name, the file is lost despite having activated Auto-Save.

1)   Is the previous statement correct for Maple 9.5?

2)   If so, has this bug been corrected in later versions?

Alla

Is it possible to perform an external call to a Java method that is not static?

When I attempt to  use the Maple function define_external with a java method that does not include the keyword 'static', Maple does not locate the method and returns an error.

Though it does not appear in the help documentation, it appears that external calls to Java methods is restricted to static methods.

Is this true?

I am using Maple 10.04.

Thanks

Bill

If you have a single variable polynomial you must specify the variable in the sort command when using the ascending and descending option.  Ascending or descending will not work without it.  It's obvious you need to express it with more than one variable but for single variables it should not be needed.

As a simple example.   b:=x+x^3+x^2;

Sort(b)  gives x^3+x^2+x and sort(b,ascending) gives the same answer as does Sort(b,descending)

A colleague of mine recently mentioned something to me about an article that circulates every year during the holiday season, entitled “The Physics of Santa Claus”. This was news to me, so I ran a few Google searches to find out what she was talking about.

It seemed that some enterprising person had taken the time to go through and explain just what is involved in Santa’s Christmas Eve trip around the world delivering presents. How many households does he have to visit? How much do all those presents really weigh? How fast do the reindeer need to fly in order to get it all done in a finite amount of time? There is much speculation as to the origins of this piece; the general consensus seems to be that it began life published in SPY magazine in the early 1990s. Whatever the true story, it’s still an entertaining read in 2008.

I’ve taken some time to update the original with more current data – for instance, it seems the world’s population has grown a bit in the last 20 years. According to the Population Reference Bureau, the world population in 2008 was approximately 6,705 billion; 28% of these are children (defined as being under 15):

In fact, making some assumptions about the percentage of these children that celebrate Christmas and the number of children per household, it turns out that Santa needs to visit close to 200 million homes in one night.

We assume he distributes gifts from 5 pm to midnight, or for 7 hours. Due to the Earth's rotation, there is an overall time difference of 24 hours between different time zones, so we can therefore say that Santa has 31 hours to finish his work (assuming he logically travels east to west). Visiting 200 million homes in 31 hours means that Santa has to visit approximately 1586 homes per second:

This gives him about 1/1600th of a second to do everything at each home, such as parking his sleigh, looking for the right gifts, climbing down the sleigh and chimney, binge on snacks, fill the stockings, come up again and rush to his next stop!

For the complete details of his annual trip, visit the Applications Center where I’ve posted the Maple document in which I’ve recreated the Santa calculations. Happy Holidays!!

Just a small issue maple could fix in an update. 

When you reach the bottom of the screen and you're typing out a long equation with many brackets the gray bar that is supposed to match them up underneath the equation is out of view.  It's nothing major and I'm sure maple already knows about this, it's probably not high on their priority list to fix but just as an FYI for them to fix for future updates.

The Maplesoft office is currently in the process of being burried in snow and many of us are getting ready to head off for the holidays.  Before leaving, I wanted to share this great animated GIF created using 3d plots.  It was sent to me by Bruce Char at Drexel University. The greeting and the Maple script to generate it are after the break.

My wife will tell you that I am horrible at remembering important things like birthdays and sending Christmas cards on time … or at all. As we approach the end of another remarkable year, it’s always rewarding to reflect on the events of the year and take the time to thank all those who made the year so remarkable. So, in no particular order