i got 3 diff ecuations with two algebraic ones. a system of DAEs. there is only a derivative included on systems, for which it's necesary only one initial condition for solving the system, which is Q(0)=0. why maple wants to know initial conditions for T_1s. it's not supposed to calculate it itself?
 

Download ecuation_2.mwecuation_2.mw

Dear Friends, I work with physics paсkage. One allows to calculate in four dimensional space-time. But in addition, I need to calculate in three dimensional space. For example, I need t0 use the next scalar products: x_Ay^A  and z_aw^a  where A=0,1,2,3 and a=1,2,3. How may I do it?

I dont understand how to approach this question, can anyone explain what it means by bessel and myJ?? Ive tried but i cant get the integral to work with the dy?

Dear all

I am trying to solve system of ODEs by TWS command for traveling wave solution, but an error is showing. When I enter sinlge ODE or PDE the command does not show any error. Why it is showing error for system of ODEs ?

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Hi everyone

I would like to unassign all  'user' variables but some of them.
More precisely, if 

• MyVars := anames('user')
• and KeepThese := {...} is some subset (manually constructed) of MyVars

I was thinking to something like
for k in MyVars minus KeepThese  do
   k := 'k'   # or k := unassign('k')
end do;

... which (obviously) does not work as desired because 'k' refers to the variable of name k and not to the variable k represents.

How is it possible to fix this ?

Great thanks in advance

Hello,

I try to retrieve some procedures from a package that I have in a 2D output.

But, when I copy/paste in a 1D maple input or a simple text file, the main part of the procedure is replaced by "...".

Example :

Package:-procedure
proc(a, b)  ...  end;

Do you have a idea to suppress this feature ? and so that I can retrieve the desired procedures?

Thanks a lot for your help

how to find roots of equation J0(xR) = 0 ,R is constant, using maple? I know command for zeros of Bessel function i.e J0(x) = 0.  but what to do with different argument?

How do I make find and replace work?  Currently the replace and find button is grayed out.  What magic gets me into a state where the button can be used?

Thanks

P.S. Is there any "package" or "mode" or way some how that emacs key bindings can be made to work (including things like find and replace)?  The user interface would be much improved if I knew how to enable that.

Hi everyone,

I need some help with the following error,

How can i solve this problem?

Thanks for your time

Best regards,

Canberk

Hello,

I would to understand a code that I have where the structure of packages are often using a local variable in a particular way. A variable local _DO_CONSTRAINT with the same name as the procedure DO_CONSTRAINT is created.

The code is the following :

module () 
local _DO_CONSTRAINT; 
export DO_CONSTRAINT; 
option package; 

_DO_CONSTRAINT:=proc (phi::list, varslist::list) 
table([obj = CONSTRAINT, expr = phi, vars = varslist]) 
end proc

DO_CONSTRAINT:=proc (phi::{list, scalar}, vars::{list, scalar}) 
if type(phi, scalar) and type(vars, scalar) then 
_DO_CONSTRAINT([phi], [vars]) 
elif type(phi, list) and type(vars, list) and nops(phi) = nops(vars) then 
_DO_CONSTRAINT(phi, vars) 
else ERROR("The number of expressions <phi> and variables <vars> are not equal") 
end if 
end proc

end module
 

Question :
1) It seems me that this technique enable to adapt the procedure  (DO_CONSTRAINT) to different types of inputs that we can try on it (lists or scalars). Do I right ? May you give me more informations on how it works ?
2) Is it the only possibility to do this ? In other words, is there a possibility to make a similar code and also concise but without using this local variable ?

Thanks a lot for your help.

I having a hard time with defining a vector, in order to store in it some data, then plot it and export it to a file, I copied all what's in the help instructures but it doesn't work everytime, please it's urgent for my PhD thesis !

E_T := (2/mu-2/r)*exp(-r/mu)*Pi^2;

How do I extract the numbers out of the equation, so it becomes

2*Pi^2*(1/mu-1/r)*exp(-r/mu) instead? 

Hi, I was wondering, as stated in the title, if it is possible to plot/draw a triangle knowing only the sides and angles, and not the coordinates for each point making up its corners. If not, what would be the easiest way, to calculate the coordinates using the sides and angles (assuming I know the value for each side and corner) and then plot/draw it?

I'm rather green when it comes to using Maple, so if you could explain it in a simple way that would be appreciated. 

I try to solve numerically a boundary VP for ODE with different order of discontinuity of right part.

Say, the following BVP is given:

y''(x)+y'(x)+y(x)=F(x)

y(0)=1, y(2)=1

Let's use piecewise right part

F  := piecewise(x<=1, -x, x>1, 2*x+(x-1)^2)

The function

piecewise(x<=1, 1-x, x>1, (x-1)^2)

as obviuos, satisfies the BVP exclung the point x=1, where its 1st and 2nd derivatives are discontinuos.

Numerical solution

N0:=6:
As:=dsolve([diff(y(x), x$2)+diff(y(x), x)+y(x)=F,  y(0)=1, y(2)=1], y(x), type=numeric, output = Array([seq(2.0*k/N0, k=0..N0)]), 'maxmesh'=500, 'abserr'=1e-3):

provides the solution essentially different to exact one described above:

But if to use the right part

F := piecewise(x<=1, x^2+x+2, x>1, -x^2+x)

for which the function

piecewise(x<=1, 1-x+x^2, x>1, -1+3*x-x^2)

satisfies the BVP excluding x=1, where this function has discontinuity of 2nd derivative only, the corresponding numerical solution is very similar to this exact solution:

This reason of the difference between these two cases is clear. In the first case both 1st and 2nd derivatives are discontiuos, while in the second one -- 1st derivative is contiuos.

I wonder, if there are numerical methods, implemeted in Maple, for numerical solution of the first type BVP with non-smooth right part?

Maple returns this: and I want to move the exp out of root so it becomes exp(

Ex3 := Pi*sqrt((4/mu+4/r)*exp(-r/mu))

and I want to move the exp out of root so it becomes exp(-r/2*mu), and I want to take the 4s out so it become 2*Pi instead of just Pi.  How do I do it? thank you for all the help