John May

Dr. John May

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17 years, 161 days
Maplesoft
Pasadena, California, United States

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I have been a part of the Mathematical Software Group at Maplesoft since 2007. I have a Ph.D in Mathematics from North Carolina State University as well as Masters and Bachelors degrees from the University of Oregon. I have been working on research in computational mathematics since 1997. I currently work on symbolic solvers and visualization as well as other subsystems of Maple.

MaplePrimes Activity


These are replies submitted by John May

@Robert Israel I probably should have been more specific, and said "Shannon Entropy" measured just with character counting a la ?StringTools:-Entropy or ?ImageTools:-Entropy .  Clearly that sort of measure can not really say anything about LZ compressibility, but so much of what I found written on the web conflated entropy (typically immediately defined to be Shannon Entropy) with compressibility when as per @JacquesC it would be better to save comparisons to compressibility for information theoritical measures of complexity (or a more subtle discussion of entropy).

@Robert Israel Excellent!

@Robert Israel Very nice!

I'll be impressed if someone can plot one of the actual 2010 World Cup balls: http://en.wikipedia.org/wiki/Adidas_Jabulani

 

John

@pvrbik There is noting particularly more intuitive about using an exprseq or list instead of an Array or Table.

WeatherHistory := Array(1..50); # or table();

for i from 1 to 50 do    
    NextWeather := TransitionFrom( TodaysWeather );    
    WeatherHistory[i] := NextWeather;   
    TodaysWeather := NextWeather;
end do:

cat(entries(WeatherHistory, 'nolist'));

 

This is, arguably, even easier to read and has the bonus of not teaching students very bad habits in Maple.

@pvrbik There is noting particularly more intuitive about using an exprseq or list instead of an Array or Table.

WeatherHistory := Array(1..50); # or table();

for i from 1 to 50 do    
    NextWeather := TransitionFrom( TodaysWeather );    
    WeatherHistory[i] := NextWeather;   
    TodaysWeather := NextWeather;
end do:

cat(entries(WeatherHistory, 'nolist'));

 

This is, arguably, even easier to read and has the bonus of not teaching students very bad habits in Maple.

@PatrickT Maybe in the UK, but things don't look good for "Jamie" in the US:

@Christopher2222 You can try highlighting the code in question and selecting the "preformatted" style or hit the "html" button to manually add <pre> </pre> tags around the code.  Those should be equivalent and should preserve the formatting.

Shouldn't this be a question and not a post?

John

It seems the images in this post were eaten in the upgrade.  It showed up as recently updated since I was trying, without luck, to replace the images.

John

I think people might avoid doing something like this due to worries about the limited life of flash memory (1-5 million writes).  Though, I have also read aritcles that suggest that if you use "write leveling" to spread writes across the whole SSD then the usable life, at maximum utilization, is on the order of several decades.

John

@Alec Mihailovs That is indeed the theory up with which we came.

Interestingly, even though the Bionic woman was spelled Jaime Sommers there was primarily a giant spike in female newborns named "Jamie" (previously, primarily a nick-name for "James").  Of course, the then less popular, "Jaime" saw a, relatively, much larger spike:

And of course, the recent tab:

http://www.mapleprimes.com/recent/unread

seems pretty close to the "tracker" view on the old Primes.

 

John

The problem seems to come from a quirk in the MeijerG method integrator.  You can work around it by explicitly asking for the FToC method in Maple 13+.

int(BesselK(1,t)*t^2, t=0..x, method=FTOC);

int(BesselK(1,t)*t^2, t=0..x, method=FTOC)

plot(2-x^2*BesselK(2,x), x=0..1)

John

Explict forms are often not very readable.  That is one of the reasons the RootOf notation is used.

John

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