MaplePrimes - Newest Posts

Mini PowerTools

Valery Cyboulko — Tue, 15 May 2012 00:06:38 Z

Example. One of thousands.
The function of two variables.
Individual works for russian biology students.
I am interested in they reaction.
HTML: 01.zip 08.zip
Maple:

Teaching Concepts with Maple

Robert Lopez — Mon, 14 May 2012 18:31:36 Z

Being easy to use is nice, but being easy to learn with is better. Maple’s ease-of-use paradigm, captured in the phrases “Clickable Calculus” and “Clickable Math” provides a syntax-free way to use Maple. The learning curve is flattened. But making Maple easy to use to use badly in the classroom helps neither student nor instructor.

In the mid to late ‘80s,...

C6 Logic 2012 hits

Valery Cyboulko — Wed, 09 May 2012 14:44:38 Z

Russian USE.
Download the archive of the html-manual: c6.zip
The main file: c6.html.
Online: http://webmath.narod.ru/do/c6.html

C5 Parameter 2012 hits

Valery Cyboulko — Wed, 09 May 2012 14:41:08 Z

Russian USE.
Download the archive of the html-manual: c5.zip
The main file: c5.html.
Online: http://webmath.narod.ru/do/c5.html

C4 Planimetry 2012 hits

Valery Cyboulko — Wed, 09 May 2012 14:34:12 Z

Russian USE.
Download the archive of the html-manual: c4.zip
The main file: c4.html.
Online: http://webmath.narod.ru/do/c4.html

C3 Inequality 2012 hits

Valery Cyboulko — Wed, 09 May 2012 14:21:37 Z

Russian USE.
Download the archive of the html-manual:c3.zip
The main file: c3.html.
Online: http://webmath.narod.ru/do/c3.html

166 hits in Maple 16

Valery Cyboulko — Thu, 03 May 2012 22:59:30 Z

In memory of a Friend. Maple 16 for Russian students.

260412.zip

Оформление - облегченное, чтобы работало на любом компьютере. Разархи и открыти файл ege.html. Неточности присутствуют, наверное. Поправим вместе.

Скачать решебник C1 (Тригонометрия) ЕГЭ сезона 2011/2012 в виде html-пособия: ...

Domain problems in plot for Maple 16

jaytreiman — Thu, 03 May 2012 00:19:32 Z

The basic plot routine in Maple 16 has a serious problem with the domain. The following is an example.

The domain is correct in Maple 15. This failure occurs in both Windows 7 and Linux.

PS driver in Maple 16 for Windows

jaytreiman — Wed, 02 May 2012 15:54:54 Z

I have been generating graphics in Maple 16 using the plotsetup(ps,...) command under Windows 7 and Linux. Maple tech support has a fix for Linux and has confirmed that there is a bug in the Windows version. These are a Windows eps (converted to png for uploading) and png of the same figure. The eps conversion should not do this.

email change

Christopher2222 — Mon, 30 Apr 2012 01:41:28 Z

There is no option to change your original email address and save in mapleprimes.

**edit add** Sorry the option is there but the option to save the new email is not.

MRB Constant Y

Marvin Ray Burns — Sat, 28 Apr 2012 21:16:41 Z

Location marker for Plot Component

acer — Thu, 26 Apr 2012 05:04:54 Z

The Locator object is a nice piece of Mathematica's Manipulate command's functionality. Perhaps Maple's Explore command could do something as good.

Here below is a roughly laid out example, as a Worksheet. Of course, this is not...

repeating wrapper (DirectSearch)

acer — Wed, 25 Apr 2012 03:30:14 Z

Here is a short wrapper which automates repeated calls to the DirectSearch 2 curve-fitting routine. It offers both time and repetition (solver restart) limits.

The global optimization package DirectSearch 2 (see Application Center link, and here) has some very nice features. One aspect which I really like is that it can do curve-fitting: to fit an expression using tabular data. By this, I mean that it can find optimal values of parameters present in an expression (formula) such that the residual error between that formula and the tabular data is minimized.

Maple itself has commands from the CurveFitting and Statistics packages for data regression, such as NonlinearFit, etc. But those use local optimization solvers, and quite often for the nonlinear case one may need a global optimizer in order to produce a good fit. The nonlinear problem may have local extrema which are not even close to being globally optimal or provide a close fit.

Maplesoft offers the (commercially available) GlobalOptimization package as an add-on to Maple, but its solvers are not hooked into those mentioned curve-fitting commands. One has to set up the proper residual-based objective function onself in order to use this for curve-fitting, and some of the bells and whistles may be harder to do.

So this is why I really like the fact that the DirectSearch 2 package has its own exported commands to do curve-fitting, integrated with its global solvers.

But as the DirectSearch package's author mentions, the fitting routine may sometimes exit too early. Repeat starts of the solver, for the very same parameter ranges, can produce varying results due to randomization steps performed by the solver. This post is branched off from another thread which involved such a problematic example.

Global optimization is often a dark art. Sometimes one may wish to simply have the engine work for 24 hours, and produce whatever best result it can. That's the basic enhancement this wrapper offers.

Here is the wrapper, and a few illustrative calls to it on the mentioned curve-fitting example that show informative progress status messages, etc. I've tried to make the wrapper pretty generic. It could be reused for other similar purposes.

Other improvements are possible, but might make it less generic. A target option is possible, where attainment of the target would cause an immediate stop. The wrapper could be made into an appliable module, and the running best result could be stored in a module local so that any error (and ensuing halt) would not wipe out the best result from potentially hours and hours worth of conputation.

restart:
randomize():

repeater:=proc(  funccall::uneval
               , {maxtime::numeric:=60}
               , {maxiter::posint:=10}
               , {access::appliable:=proc(a) SFloat(a[1]); end proc}
               , {initial::anything:=[infinity]}
              )
          local best, current, elapsed, i, starttime;
            starttime:=time[real]();
            elapsed:=time[real]()-starttime;
            i:=1; best:=[infinity];
            while elapsed<maxtime and i<=maxiter do
              userinfo(2,repeater,`iteration `,i);
              try
                timelimit(maxtime-elapsed,assign('current',eval(funccall)));
              catch "time expired":
              end try;
              if is(access(current)<access(best)) then
                best:=current;
                userinfo(1,repeater,`new best `,access(best));
              end if;
              i:=i+1;
              elapsed:=time[real]()-starttime;
              userinfo(2,repeater,`elapsed time `,elapsed);
            end do;
            if best<>initial then
              return best;
            else
              error "time limit exceeded during first attempt";
            end if;
          end proc:


X := Vector([seq(.1*j, j = 0 .. 16), 1.65], datatype = float): 

Y := Vector([2.61, 2.62, 2.62, 2.62, 2.63, 2.63, 2.74, 2.98, 3.66,
             5.04, 7.52, 10.74, 12.62, 10.17, 5, 2.64, 11.5, 35.4],
            datatype = float):

F := a*cosh(b*x^c*sin(d*x^e));

                                    /   c    /   e\\
                         F := a cosh\b x  sin\d x //

infolevel[repeater]:=2: # or 1, or not at all (ie. 0)
interface(warnlevel=0): # disabling warnings. disable if you want.

repeater(DirectSearch:-DataFit(F
                      , [a=0..10, b=-10..10, c=0..100, d=0..7, e=0..4]
                      , X, Y, x
                      , strategy=globalsearch
                      , evaluationlimit=30000
                              ));
repeater: iteration  1
repeater: new best  9.81701944539358706
repeater: elapsed time  15.884
repeater: iteration  2
repeater: new best  2.30718902535293857
repeater: elapsed time  22.354
repeater: iteration  3
repeater: new best  0.627585701120743822e-4
repeater: elapsed time  30.777
repeater: iteration  4
repeater: elapsed time  47.959
repeater: iteration  5
repeater: new best  0.627585700905294148e-4
repeater: elapsed time  55.221
repeater: iteration  6
repeater: elapsed time  60.009
 [0.0000627585700905294, [a = 2.61748237902808, b = 1.71949329097179, 

   c = 2.30924401405164, d = 1.50333106110324, e = 1.84597267458055], 4333]


# without userinfo messages printed
infolevel[repeater]:=0:
repeater(DirectSearch:-DataFit(F
                      , [a=0..10, b=-10..10, c=0..100, d=0..7, e=0..4]
                      , X, Y, x
                      , strategy=globalsearch
                      , evaluationlimit=30000
                              ));

 [0.0000627585701341043, [a = 2.61748226209478, b = 1.71949332125427, 

   c = 2.30924369227236, d = 1.50333090706676, e = 1.84597294290477], 6050]


# illustrating early timeout
infolevel[repeater]:=2:
repeater(DirectSearch:-DataFit(F
                      , [a=0..10, b=-10..10, c=0..100, d=0..7, e=0..4]
                      , X, Y, x
                      , strategy=globalsearch
                      , evaluationlimit=30000
                              ),
         maxtime=2);

repeater: iteration  1
repeater: elapsed time  2.002
Error, (in repeater) time limit exceeded during first attempt

# illustrating iteration limit cutoff
infolevel[repeater]:=2:
repeater(DirectSearch:-DataFit(F
                      , [a=0..10, b=-10..10, c=0..100, d=0..7, e=0..4]
                      , X, Y, x
                      , strategy=globalsearch
                      , evaluationlimit=30000
                              ),
         maxiter=1);

repeater: iteration  1
repeater: new best  5.68594272127419575
repeater: elapsed time  7.084
 [5.68594272127420, [a = 3.51723075672918, b = -1.48456068506828, 

   c = 1.60544055207338, d = 6.99999999983179, e = 3.72070034285212], 2793]


# giving it a large total time limit, with reduced userinfo messages
infolevel[repeater]:=1:
Digits:=15:
repeater(DirectSearch:-DataFit(F
                      , [a=0..10, b=-10..10, c=0..100, d=0..7, e=0..4]
                      , X, Y, x
                      , strategy=globalsearch
                      , evaluationlimit=30000
                              ),
         maxtime=2000, maxiter=1000);

repeater: new best  3.10971990123465947
repeater: new best  0.627585701270853103e-4
repeater: new best  0.627585700896181428e-4
repeater: new best  0.627585700896051324e-4
repeater: new best  0.627585700895833535e-4
repeater: new best  0.627585700895607885e-4
 [0.0000627585700895608, [a = 2.61748239185387, b = -1.71949328487160, 

   c = 2.30924398692221, d = 1.50333104262348, e = 1.84597270535142], 6502]

A Hybrid between HTTP:-Get and ImportMatrix

alex_01 — Tue, 24 Apr 2012 16:46:29 Z

I came across a thing that does not make sense in Maple. If you click on:

http://ichart.finance.yahoo.com/table.csv?s=CSV&a=10&b=15&c=1996&d=03&e=24&f=2012&g=d&ignore=.csv

Then you will get a csv-file.

Now if you download and save that file on your computer then you can open it with:

Cloud Database

alex_01 — Sun, 22 Apr 2012 21:08:02 Z

I am surfing around looking for cloud database providers (a lot of them are free
such as http://xeround.com) Then it struck me that maple has a cloud. Unfortunatly I
dont think it can handle what I want it to do:

Wouldnt it be cool if every maple user could have a personal or public data warehouse
in the maple cloud instead of everyone having sql servers running localy with attached
cron jobs and head aches.

It...