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DJKeenan

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17 years, 207 days
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These are answers submitted by DJKeenan

closed form of sum...

DJKeenan 442
October 26 2007
0 0
I tried looking the series up in Hansen's Table, but no luck. Given how simple the definition, this seems like evidence that no one knows a closed form. Another approach, admittedly unlikely, is to use identify(evalf(sum(...))). But this too gave no answer.

Minimizing the maximum...

DJKeenan 442
October 21 2007
0 0
If the ranges for r and zeta are, for example, -2..3 and -6..7, then how about something like this? with(Optimization): g:= zeta -> Maximize(a(r, zeta), r = -2 .. 3, method = 'branchandbound')[1]; Minimize(g, -6 .. 7, method='branchandbound')[1]; Note that method is used to get a global solution.

Monty Hall Problem...

DJKeenan 442
October 12 2007
1 0
For some general background, it is worth noting that this is the “Monty Hall Problem”.

Optimization call...

DJKeenan 442
October 07 2007
0 0
How about this? Optimization[Maximize](objective(x1, x2, x3, x4, x5, x6, x7, x8, x9), seq(x || i = 0 .. 7, i = 1 .. 9), initialpoint = [seq(x || i = some_point[i], i = 1 .. 9)]); [0.99999999999979594, [x1 = 0.249910963699999988, x2 = 2.07892373100000016, x3 = 2.25241025000000006, x4 = 5.71395350600000018, x7 = 3.14159233835433582, x8 = 3.14159233239993796, x9 = 3.14159261604398532, x5 = 0.347503411099999992, x6 = 1.57079632730711150 ]]

Real fixed points...

DJKeenan 442
September 16 2007
0 0
To add to Robert Israel's answer, if you want only solutions in R4, try RealDomain. use RealDomain in solve(F - [x1,x2,x3,x4]) end use;           {x3 = 0, x1 = 0, x2 = 0, x4 = 0}

changecoords...

DJKeenan 442
September 10 2007
0 1
Does changecoords help? This can do conversion to cartesian, from just about anything. changecoords([r, theta], [r, theta], 'polar')           [r*cos(theta), r*sin(theta)] changecoords([r, phi, theta], [r, phi, theta], 'spherical')           [r*sin(theta)*cos(`ϕ`), r*sin(theta)*sin(`ϕ`), r*cos(theta)]

hah!...

DJKeenan 442
September 02 2007
0 0
… but about exp(Pi), this is transcendental, by the the Gelfond–Schneider theorem (which solved the seventh of Hilbert's problems). Gelfond also had a separate proof for exp(Pi), a few years earlier (cited here).

Point-and-click methods...

DJKeenan 442
August 27 2007
0 0
A good general guideline for GUIs is that (almost) anything that can be done via point-and-click should also be doable via some sequence of keystrokes.

Statistics:-PointPlot...

DJKeenan 442
August 22 2007
0 0
Have you looked at Statistics:-PointPlot? If x and y are lists, then Statistics:-PointPlot(y,xcoords=x) should work well. I just tried it with 5000 points (in Maple 11), and it worked fine; response time was <2 seconds.

fsolve with Int...

DJKeenan 442
August 21 2007
0 4
Here is a simpler example that illustrates the issue. fsolve(Int(t, t = 0 .. x) = 1); Error, (in fsolve) number of equations, 1, does not match number of variables, 2 But there is an easy solution: fsolve(x->Int(t, t = 0 .. x) = 1);

Product suggestion—lowess...

DJKeenan 442
August 17 2007
0 0
I have posted more about this in Product Suggestions.

Homework?...

DJKeenan 442
August 13 2007
0 1
Is this a homework assignment? (If so, does your teacher approve of asking on MaplePrimes?)

Re: Is Maple 11 the answer?...

DJKeenan 442
August 08 2007
0 0
Brian, for some thoughts about using documents and the Standard Interface in Maple 11, see my blog entry related to this.

collapsible section...

DJKeenan 442
August 02 2007
0 0
Another approach to the problem is to put the computation into its own section (or subsection). Then collapse the section.

minimum vs. minimal...

DJKeenan 442
June 14 2007
1 0
There seems to be some terminological confusion. Yath is asking for all minimal cuts, whereas mincut finds a minimum cut. Maple does not have a built-in function for the "minimal cuts" problem. I googled a little and found some papers that have algorithms; here are two doi: 10.1007/BF01074775 10.1109/LCN.2000.891015 There might be others; I only spent a few minutes googling. Too, there might be different approaches that take advantage of some other functions in Maple.
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