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Alec Mihailovs

Dr. Aleksandrs Mihailovs

4455 Reputation

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20 years, 309 days
Mihailovs, Inc.
Owner, President, and CEO
Tyngsboro, Massachusetts, United States

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Contact Dr. Aleksandrs Mihailovs

I received my Ph.D. from the University of Pennsylvania in 1998 and I have been teaching since then at SUNY Oneonta for 1 year, at Shepherd University for 5 years, at Tennessee Tech for 2 years, at Lane College for 1 year, and this year I taught at the University of Massachusetts Lowell. My research interests include Representation Theory and Combinatorics.

MaplePrimes Activity


These are answers submitted by Alec Mihailovs

fsolve...

Alec Mihailovs 4455
November 24 2006
0 1
You can see from the plot that they intersect in one point. That point can be found by using fsolve, 
fsolve(x^4=6^x);

                            -0.7232652008

%^4;

                             0.2736467407
__________ Alec Mihailovs http://mihailovs.com/Alec/

Solutions with 0 initial conditions...

Alec Mihailovs 4455
November 23 2006
0 0
With your initial conditions, theta(t)=0 is the solution given by adding option numeric to dsolve, so it plots 0. With axes it looks as if it is an empty plot, but you can see it after removing the axes, 
plots[odeplot](soln,0..1,axes=boxed);
__________ Alec Mihailovs http://mihailovs.com/Alec/

evalc...

Alec Mihailovs 4455
November 22 2006
0 5
There is a way to convert it to φ though,
evalc(argument(exp(phi*I)));

                                 φ
__________ Alec Mihailovs http://mihailovs.com/Alec/

Kayali...

Alec Mihailovs 4455
November 22 2006
0 0
It shouldn't be very hard to extend Kayali to run Maple instead of Maxima. __________ Alec Mihailovs http://mihailovs.com/Alec/

How to plot that...

Alec Mihailovs 4455
November 21 2006
0 1
As J. Tarr said, for equations of first order dsolve's answer doesn't include the derivative. For example, 
sol1(0);

                         [t = 0., m(t) = 1.]
Since it doesn't produce the derivative, it can not be included in the odeplot command. If one wants to plot the derivative, too, it should be entered as an expression from the DE, 
dm:=eval(diff(m(t),t),mtest):

plots[odeplot](sol1, [[t, m(t),color=green],[t,dm,color=blue]], 0 .. 1);
The same thing works in the original example (with a system of 2 DE of first order), too. __________ Alec Mihailovs http://mihailovs.com/Alec/

Product Suggestions forum...

Alec Mihailovs 4455
November 20 2006
0 0
That should be, probably, put in the Product Suggestion forum. From other point of view, it doesn't seem very active. My posts there didn't get any responses. __________ Alec Mihailovs http://mihailovs.com/Alec/

codegen, Spread, and LargeExpressions...

Alec Mihailovs 4455
November 18 2006
0 4
codegen package has commands optimize and split that can be used. Spread package can be used for working with spreadsheets. Also, LargeExpressions package might be useful. See corresponding help pages ?codegen,optimize , ?codegen,split , ?Spread , and ?LargeExpressions . __________ Alec Mihailovs http://mihailovs.com/Alec/

Here it is...

Alec Mihailovs 4455
November 17 2006
0 0 
Calc:=proc()
  local t;
  global m,Timer;
   use Maplets, Maplets:-Elements in
    Timer:=proc()
      t:=iolib(25);
      while iolib(25)-t<3 do od end;
    m:=Maplet(
      'onstartup'=Action(RunWindow('Splash'),
        Evaluate(function="Timer"), CloseWindow('Splash'),
        RunWindow('Main')),      
      Window['Splash']('title'="Welcome",
        [Label(Image("H:\\image.jpg"))]),

######################### MAIN WINDOW ######################
      Window['Main']('title'="Calculator",
       # 'width'=640, 'height'=480,
GridLayout(
  GridRow(
    GridCell(     #4
      "  # of Batteries:"),
    GridCell( 
      DropDownBox['DDB1']("1", 
        sort(["1", "2", "3"], lexorder))),     #3
    GridCell(     #5
      "  # of Resistors:"),
    GridCell(
      DropDownBox['DDB2']("1", 
        sort(["1", "2"], lexorder))),     #4
    GridCell(
      "  Parallel/Series "), 
    GridCell(
      DropDownBox['DDB3']("Parallel", 
        sort(["Parallel", "Series"], lexorder)))),     #4
  GridRow(
    GridCell(
      Label(Image("H:\\image2.jpg"))),
    GridCell(
      "  Field 1  "), 
    GridCell(
      TextField['TF1'](10))))));
Display(m) end use end:

Calc();
I just slightly changed code formatting, deleted one square bracket, moved a comma, and included text labels in a separate cells. Good luck with your project, __________ Alec Mihailovs http://mihailovs.com/Alec/

Underover...

Alec Mihailovs 4455
November 16 2006
0 0
Without changing the size, it can be done in Standard Maple 10 as 
`print/Q`:=proc(a,b)
cat(`#munderover(mn(Q),mn(`,a,`),mn(`,b,`))`) end:

Q(4,2);
                    2 
                    Q
                    4
I'm not sure whether changing the size is implemented, but even if it is, I don't know how - I tried a few different things, but they didn't work. This is undocumented, so it may be changed in future Maple versions. __________ Alec Mihailovs http://mihailovs.com/Alec/

converting to a list...

Alec Mihailovs 4455
November 16 2006
0 0
arrays (with a small a) are not something recommended for using in Maple. Arrays (with a capital A) are recommended, and in some situations - lists. A list can be created as either 
m:=[op(a+b+c)];

                            m := [a, b, c]
or 
m:=convert(a+b+c,list);

                            m := [a, b, c]
Arrays and arrays can be constructed from the list, 
array(m);

                              [a, b, c]

Array(m);

                              [a, b, c]
__________ Alec Mihailovs http://mihailovs.com/Alec/

eps...

Alec Mihailovs 4455
November 15 2006
0 0
Yes, conversion to eps is not that great in Maple 10 and I don't think that it can be easily fixed. It was much better in earlier Maple versions, Maple V Release 5.1 or Maple 6. If you can't find them, you might try Matlab - as far as I can tell, people usually use it for that. Besides, one can enter text in LaTeX in Matlab and it appears properly displayed in the eps. __________ Alec Mihailovs http://mihailovs.com/Alec/

networks...

Alec Mihailovs 4455
November 15 2006
0 0
Sure, a lot of commands in the networks package, see ?networks __________ Alec Mihailovs http://mihailovs.com/Alec/

VectorCalculus...

Alec Mihailovs 4455
November 15 2006
0 0
You may look in the VectorCalculus package, especially such things as TNBFrame and DirectionalDiff. __________ Alec Mihailovs http://mihailovs.com/Alec/

It can be plotted...

Alec Mihailovs 4455
November 15 2006
0 0
It can be plotted, for example, as 
obj := b -> x^2-b*y:
constr := b -> b*x+y = 0:
SL := b -> Optimization:-NLPSolve(obj(b), {constr(b)})[1]:
SL(3);

                         -20.2499999999999929

plot(SL,0..100);
__________ Alec Mihailovs http://mihailovs.com/Alec/

An example...

Alec Mihailovs 4455
November 15 2006
0 5
For example, 
f:=(cos(t)+cos(3*t)+cos(4*t))/Pi:
S:=inttrans[fourier](f,t,w);

  S := Dirac(w + 4) + Dirac(w - 3) + Dirac(w + 3) + Dirac(w - 4)

         + Dirac(w + 1) + Dirac(w - 1)

F:=S->map(x->plottools[line]([-op([1,2],x),0],[-op([1,2],x),1]),[op(S)]):

plots[display](F(S),color=blue,
tickmarks=[[-4="-w3",-3="-w2",-1="-w1",1="w1",3="w2",4="w3"],[0=0]],
labels=[`w[Rad/sec]`,Amplitude],view=[-6..6,0..1]);
I wonder what happened with -w1 (Classic Maple plotting specifics?) Font also could look better. See also Plotting the Dirac Function thread. If you are interested in drawing arrows at the end of the axes and putting labels there, see How to control the thickness of axes and tickmarks thread. ____________ Alec Mihailovs http://mihailovs.com/Alec/
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