I have an old blog entry about that. Also, I posted about that in the Maple newsgroup a couple of years ago.

Alec

Many ways, and it can be done in one step as well,

selectremove(type,eq1,`^`);
                          2                2
                         x , (3 + Pi) sin(x )

or

selectremove(patmatch,eq1,x^2);
                          2                2
                         x , (3 + Pi) sin(x )

or

selectremove(`=`,eq1,x^2);
                          2                2
                         x , (3 + Pi) sin(x )

Alec

Frankly, I don't understand how IF could be used in Excel for selecting, or removing some data. To use IF, one has to select the cell where it should be used, and then type the formula =IF(...) there. But if the cell is selected, why would one need IF to change it's content? Just type there something new, or copy it in case if it needs to be retrieved.

Alec 

Why would one need a procedure for that?

A[3,4]:=0;

works as well as RemMat(A,3,4).

Alec

Try to use signum instead of sign.

Also, sign would work if you quoted it with single quotes, as 'sign'.

What happens is that Maple evaluates plot arguments before executing them, and sign(H) is 1. If it is quoted, it evaluates to sign(H) instead of 1.

Alec

Did you try fsolve?

One thing that should be changed is I - in Maple it is the square root of -1, so if you mean something different, you should rename it.

Also, Optimization package could be used, perhaps.

Alec

There are some hacks for that known, and they depend on the type of equations you have. What is g?

In general, I wouldn't do it that way. First 3 equations are quite simple and can be solved even mentally, without Maple. Maple also can be used, of course,

solve(2*x+3*lambda*x^2,x);
                                    2
                            0, - --------
                                 3 lambda

Then you could substitute that in g and get an equation with only one unknown, lambda.

By the way, if it is a Lagrange multipliers problem. Maple has a special command for that, see ?LagrangeMultipliers

Alec

That was discussed many times on this site. If you put  "export plot" or "export data" in the input field at the top of the page and click Search, you will get a lot of references.

Alec

That depends on what you mean by a table. If you mean a Matrix, say Matrix A, then the element in 3rd row and 4th column can be retrieved as A[3,4].

Alec

Also, during a Maple session, the memory used can be restricted using kernelopts(datalimit). When the limit is reached, the kernel shuts down, but the GUI works, and it is possible to save the worksheet(s). There is a help page about that, ?alloc

Alec

First, what you wrote, is not an equation - just an expression. An equation should have a = sign in it.

Second, instead of I*(Pi-5)^.5 one would normally use -sqrt(5-Pi). 

Third, I don't exactly understand what you are trying to do.

Alec

Symbolics in Maple doesn't go further than numbers (complex) and functions of them. All linear algebra etc. is numerical only.

Some functionality that you need, can be provided using define command. But you have to do it yourself, and if you go rather deep into this, you'll meet a lot of bugs on your way - at least I did.

Alec

Maple V used pdesolve, and now it is obsolete. Maple 12 is using pdsolve.

Alec

pdsolve(-a*u(t,x)+diff(u(t,x),t)+b*diff(u(t,x),x,x)=0,u(t,x));

                                     d
  (u(t, x) = _F1(t) _F2(x)) &where [{-- _F1(t) = _c[1] _F1(t),
                                     dt

         2
        d              _F2(x) _c[1]   a _F2(x)
        --- _F2(x) = - ------------ + --------}]
          2                 b            b
        dx

Alec

For example, the following works,

Digits:=14:

fsolve({192.5 = 6.8889*10^8*(X1/(exp(1199.562077/Y1)-1)+X2/(exp(1199.562077/Y2)-1)),
977.9 = 1.755442918*10^7*(X1/(exp(575.7897971/Y1)-1)+X2/(exp(575.7897971/Y2)-1)),
4642.7 = 2.20449676*10^5*(X1/(exp(239.9124155/Y1)-1)+X2/(exp(239.9124155/Y2)-1)),
6139.8 = 17143.12466*(X1/(exp(143.9474493/Y1)-1)+X2/(exp(143.9474493/Y2)-1))},{X1=500,X2=6000,Y1=500,Y2=50});

  {X1 = 0.0070605604416211, X2 = 25.735498938176,

        Y1 = 118.33146036522, Y2 = 33.501726500995}
 

However, X1 is slightly out of the specified interval.

Alec