It seems that the answer to my question is deleted!!!

So, I again repeat it.

How I can calculate this integral?

I want to calculate integral with the constants Aj]j=1,2.

The Amount of these constants  unknown this stage.

Thanks

INTEGRAL

integral.mw

I am trying to evaluate any which way the integral:

The program just hangs, so i click on 'stop current operation'.

Then I tried:

evalf(Int(exp(-(sqrt(4*x^2+4*y^2+4*z^2)^3)), z = -sqrt(4-x^2-y^2).. sqrt(4-x^2-y^2),y=-sqrt(4-x^2)..sqrt(4-x^2),x=-2..2));

It returns the integral back unevaluated.

It's true that I could use a change of variables, changing to spherical coordinates would be best here. But I would like to know if I did set up the original Cartesian integral correctly. Is there some workaround I can apply to get a numeric answer. I am satisfied with a decimal approximation. Then I can compare to the change of variable result. An exact answer would be even better of course.

THis is another ode which I am not able to get odetest to give zero. Any one knows of a trick to verify this solution? It might be just that the solution is too complicated for odetest to verify?

Download 072619.mw

Maple 2019.1, Physics 395

Download 072619.mw

This must be a simple question. I have a simple expression:

test := -2+exp(theta)+exp(-theta)

and want to get that factored as a polynomial in the variable exp(-theta).

That is of course easy by hand, but the same problem appears frequently, as a part in further simplifications. There must be an easy way to do it, but I cannot find it. 

How to draw the given data?

Download aaa.mw

pde := diff(u(x, t), x $ 4) = diff(u(x, t), t $ 2);

iv:= subs(L = 100, {u(0, t) = 0, u(L, t) = 0, u(x, 0) = sin(x), D[2](u)(x, 0) = 2*x, D[1, 1](u)(0, t) = 0, D[1, 1](u)(L, t) = 0});

de := pdsolve(pde, iv, numeric):

sa1 := de:-value(output = listprocedure);

sa1:=[x=proc() ... end proc,t=proc() ... end proc,u(x,t)=proc() .. end proc]

    With the above procedure it works, but in the most compact form below it does not work.

pdsolve(pde, iv, numeric,output = listprocedure):

Error, (in pdsolve/numeric/par_hyp) invalid arguments for theta scheme: [output = listprocedure]
 

I have been using simplify() in number of places, and not really expecting it will do any harm. At worst, it will have no effect, or it will change the expression to different form, but the semantics will remain the same.

Until I noticed that odetest() fail on some of my solutions because I called simplify  on the solution before.

One example why this happens, is that Maple simplifies cos(2*x)*sqrt(1/cos(2*x)^2) to csgn(1/cos(2*x)) and this makes odetest fail. Adding assuming x::real has no effect on making odetest happy.

So now I changed simplify(sol) to simplify(sol,size) and this seems so far not to have this adverse effect. 

My main reason for calling simplify  is to make the expression smaller. In Mathematica that is what I do, In Mathematica there is no "size" option to Simplify.

So now, I am very worried about calling simplify() as is.

Could some Maple experts share some of their experience on this? Should one call simplify() only when an explicit option, like size, trig, exp, etc....is also used and not call simplify as is?

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Hello. Let's say I have expressions of different lengths - linear combinations of some functions with some coefficients. And there is a free member. Is there a way to get out of these expressions free member? That is func(A)=78.34

Dear Users!

I have made a code using loops. But when I exceute it I go unwanted expression please see the files and try to fix it. I shall be very thankful. 

Help.mw

Special request to:

@acer @Kitonum @Preben Alsholm @Carl Love

My question seems simple but after using google and maple help I was still unsuccesfully in plotting a simple line with a function on the same coordinate.

 1. Let f(x) = xe^x^3 and denote by A the area bounded by f(x) = xe^x^3 , x-axis and the
line x = 1.
(a) Graph the function f over the interval [-1; 1].

I have no idea on how to plot  f(x) with the line x=1 on the same coordinate.

What is the solution to this error message when trying to run the Maple add-in for Excel?
"The specified module could not be found.  OpenMaple cannot find Maple engine library, maple.dll."

I am running Maple 19.1 and Excel 2016, both 32-bit, in Windows 7.  Excel appears to have successfully installed the Maple add-in.  For example, the Maple add-in icons appear on the Add-ins tab of Excel.  Excel shows the Maple add-in as active in the list of add-ins.  The location of he WMIMPLEX.xla is correct at "C:\Program Files (x86)\Maple\Excel\WMIMPLEX.xla.

Maple support tells me that Maple should add its "bin" folder to the PATH key for excel.exe in the registry key "Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\excel.exe\Path".  This path information, however, is not in my computer's registry.  This missing path information might be an obvious problem.  But what is the correct registry entry so that Excel knows where to find the Maple engine library maple.dll?

I tried adding the path to maple.dll in the environmental path variables of Windows 7, but that approach did not work.  I have uninstalled, rebooted, and reinstalled Maple 2019 (32-bit) several times.  Still the same error message.

Thanks.

My name is Viorel Popescu and I am a Ph.D. candidate at University Politehnica of Bucharest, Europe. I was impressed by the article that I found on the internet about Series Solution to Differential Equation with Maple. I am trying to solve the equation g''(r)- r/R*g(r)=0 with initial condition g(2R)=0 and g'(0)=R where R>0 is a positive constant.

with(PDEtools);
pde := diff(c(x, t), x, x) - h*diff(c(x, t), x) = diff(c(x, t), t):

iv := c(0, t) = 0, c(a, t) = 0, c(x, 0) = c0:

de := pdsolve([pde, iv], c(x, t), build);

                         de := ( )

Does anyone know how to solve this PDE?
Thank you,

Oliveira

Is there any way to place a command to the right of an expression to perform a task? Because I only know the way that puts the command to the right.A simple example:

w1 := simplify(sin(x)² + cos(x)²);

                       w1:=1

w2:=sin(x)²+cos(x)²:-simplify;
             Error, invalid module reference

I wonder if there is a way to put the commands, also to the right of the expressions, as above.

Thank you,

Oliveira
   

Hi,

I seeking for informations on the Statistics:-ChiSquareSuitableModelTest procedure:

1. Once you have choose the number of bins, what strategy does this procedure use to define the bins (equal width, equal probability, other one?).
    
2. It seems the procedure accepts any value for this number of bins and that its correct use then is under the sole responsability of the user. Am I right?

In the book below (but I'm sure this can also be found on the web) there is a detailed discussion concerning "good practices" in using the Chi-Square goodness of fit test: does anyone known is something comparable is used in ChiSquareSuitableModelTest ?

Statistical methods in experimental physics, W.T.Eadie, D. Drijard, F.F.James, M. Roos, B. Sadoulet
North-Holland 1971
Paragraph 11.2.3 "choosing optimal bin size"


Thanks in advance