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MaplePrimes Activity

These are replies submitted by Christopher2222

@brian bovril 

Gamma right now works out to about 0.2. 




For your example just above it looks like you wanted an assignment.




Thanks. Nice bit of history there.  600 lines of code!  That's crazy and impressive.

Thanks for the hints that helps so for an example this is what I've got





a := plot(x^3, x = 0 .. 30)

new2d := transform(proc (x, y) options operator, arrow; [x, y^(1/3)] end proc)

b := new2d(a)

display({b}, tickmarks = [default, [seq(i = i^3, i = 1 .. 30)]])
display({b}, tickmarks = [default, [seq(i = i^3, i = 1 .. 30)]])






Italy's mortality rate is so high because they have a much older population of people living there.

I was basing my 3 week guess on China's pattern.  Understanding crowd dynamics is pretty chaotic when driven by fear.  But the big fear is not having enough tools to handle the influx of people that will require hospitalization. 

@mmcdara Thanks, I was wondering when someone at Maple was going to do something. It was in my bag of things to do in Maple.  And funny you should mention, I was following information there for a while - people at work asked me where I got my info from and just last week I let the cat out of the bag. 

Also, if people are interested, you can find situation reports here

The only thing I've done in Maple is just a quick doubling calculation.  That is if the Covid-19, or the official name of the virus known as SARS Cov-2, growth is exponential and continues to be exponential then we can expect the whole world to have been infected in roughly over a year. 

So the doubling rate for the world excluding China turned out to be 4 (that is every 4 days the number of cases would double) including China that number becomes 21 and only because of the draconian measures China put in place, which only until now countries are starting to believe is the only way to contain/slow the virus. 

Anyways, the math...

eq := Nt = N0*2^(t/Td)
N0 := 21000: #this was when the world only had 21,000 cases outside of China - from Feb 23 when I carried this out
Td := 21: #we'll use the conservative number of 21 which includes China
Nt := 7700000000: #rough population of the world


So, from Feb 23, if the virus doubing of 21 is used and it's growth is exponential we can expect the population of the world to all have been infected in 388 days - however that's using those draconian measures that the Chinese have done.

Now of course if we use the doubling value of 4.  The world population gets infected much sooner again remembering if the growth rate stays exponential.

Td:=4:#doubling rate of 4


So using 4days as the doubling rate - which is worst case scenario, in a little over 2 months the whole world will have had the virus.

Using todays numbers N0:=155792 #current value shown on


In 62 days from now (worst case scenario) the whole world is infected.  Using the more conservative measure of 21 (it will likely be between 4 and 21) then ...

Using Td:=21:


AdvanceDate("Mar 14, 2020", 327)

AdvanceDate("Mar 14, 2020",62)

Also looking at the graph (sorry I haven't time to clean it up and post) in 3 weeks North America will be in a full outbreak situation.



Argh!  I must have dyslexia.  Yes my confusion.  I mixed up the yy and xx's.  Sorry


If I use these values there is a problem.  The graph seems to not plot the graph beyond y=24

yy := [3, 3, 3, 4, 6, 7, 8, 6, 7, 13, 8, 9, 6, 7, 12, 14, 16, 34, 42, 23, 32, 45];
xx := [seq(i, i = 1 .. nops(yy))]:

Since I realize you and maplesoft are always working on improving a Maple debugger that's relatively and mostly unintersting and boring ... I try to give you a change and inject ideas that are mostly exciting to users and/or staff that might realize some interesting potential.  I enjoy your engineering apps you come up with, and some quite creative!  Thanks for your all of your input and keep them coming.  The engineering aspect of your ideas you bring to Maplesoft are a talent not to be lost. 

I'm far from using the potential of Maple, and Maple 2020 looks great.  Haven't chance to upgrade yet, but look forward to it.  How about an Astronomy package?

@acer yes sometimes my questions are a little unclear, sorry about that.  However you've hit the nail on the head with your answer to my follow up question, that is what I was looking for.  Thanks.

Would that solution be the simplest, sorry most efficient way?

Thumbs up but Acer has the more elegant solution.  Thanks for the insight and I appreciate the work you put into finding a solution for me.  

I was thinking of using spacecurve as well but couldn't come up with anyting simple.

Ok so lets say for example I have this profile

x := [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
y := [3, 3, 3, 4, 5, 6, 8, 7, 6, 5];

s := Spline(x, y, v):

g := plot([s], view = [0 .. max(x), 0 .. max(y)])

So what I want is the x and y flipped so the line profile is drawn from x=3 at y=0 to x=5 at y=9.   Then revolve it around the y axes.  And animate the 3d profile from the x-z plane at y=0 to y=9.

Maple froze on me again.  I was only just starting a new 2d worksheet, I had a few others open at the time.  As I was typing a flyout word came up to suggest what I wanted and then it froze. 

I checked task manager and the memory usage for java was around 1.6Gb.  Does this have something to do with maxheapsize?  I thought that was all fixed and only mattered with older versions of Maple?

@tomleslie Thanks, the second one is the one I was after.  I suppose the SurfaceOfRevolution could be replaced with a Spline curve if one chose to do so. 

The only thing missing from the audiotools package is support for mp3 format.

@stefanv initially I was going to have to resort to tomleslie's, or a variant of his, solution.  Or use Describe.  The Interface(rtablesize=0) does produce a nice compact output display however - or I could just supress it  with the colon.

That's a neat trick you have shown - that command option does not exist anywhere in the help file system so thanks again for that trick.

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