Hi

 

thank you for you reply.

In the worksheet I import some packages (via the with(...) sintax)  I've made, which passes at the main worksheet exports that contain M. It could be that this M is viewed as a different constant in the main worksheet, even if in the package I used the

global M;

declaration?

S.

ps: If I select from thist Firefox page the expression I wrote before (that is a 2D output that I copied from my worksheet after have choising "convert as string"):

(-R*(36*M^3*G^3*R^2-18*M^2*G^2*R^3-6*M^2*G^2*R*xi^2+2*R^4*M*G+4*M*G*R^2*xi^2+xi*R*(-R^2*(-R+2*M*G)^2*(-4*R^2+12*M*G*R-xi^2))^(1/2)-6*xi*M*G*(-R^2*(-R+2*M*G)^2*(-4*R^2+12*M*G*R-xi^2))^(1/2)-R^3*xi^2))^(1/2)/R^2*(3*M*G-R)/(-R^2*(3*M*G-R)^2*(-2*R^3*M*G+2*M*G*R*xi^2-R^2*xi^2+6*M^2*G^2*R^2-xi*(-R^2*(-R+2*M*G)^2*(-4*R^2+12*M*G*R-xi^2))^(1/2)))^(1/2)

and I copy it in my worksheet page, and I use the subs command, it works.

So the problem is really how maple treats the 2D output as input for a new command.

I've assumed what follows:

assume(R::real);
additionally(R::positive):
additionally(R>2*M*G):

For me too it works if I rewrite by hands the output of the former result, instead of use the ditto operator.

But, as you certainly see, it's impossible to spend every time several minutes doing this; this is particularly true for me, as I work with cumbersome expressions

If I have as a 2D output the following expression:

 

(-R*(36*M^3*G^3*R^2-18*M^2*G^2*R^3-6*M^2*G^2*R*xi^2+2*R^4*M*G+4*M*G*R^2*xi^2+xi*R*(-R^2*(-R+2*M*G)^2*(-4*R^2+12*M*G*R-xi^2))^(1/2)-6*xi*M*G*(-R^2*(-R+2*M*G)^2*(-4*R^2+12*M*G*R-xi^2))^(1/2)-R^3*xi^2))^(1/2)/R^2*(3*M*G-R)/(-R^2*(3*M*G-R)^2*(-2*R^3*M*G+2*M*G*R*xi^2-R^2*xi^2+6*M^2*G^2*R^2-xi*(-R^2*(-R+2*M*G)^2*(-4*R^2+12*M*G*R-xi^2))^(1/2)))^(1/2)

and then try subs(R=1/U,%) it replace NONE of the R's!

I can't explain better my problem, so I hope you've understood it.

S.V.

Thank you

your answer is really simple and enlightening.

I'll read very carefully the ?use page

 

S.V.

I have no reasons. I hoped!!

I thought maple would said to me if it don't found any closed solution...

S

Thankyou both,

 

in fact I normally start maple with "xmaple" command on BASH, and it was with it that I experienced this problem.

I'll try with the Classical interface, but it's a pity that a simple operation like simplify don't work well in the workshet :(

 

S.

I'm a Linux fedora user, so I don't have the many-choices Windows menu!

 

S.

I will try, but I don't know how to choose the standard interface instead of the newer one!!!

 

thank you for the help

S.

Thank you.

 

It could be a problem due to the fact that the output is a 2-D output (the imput is a "maple imput")?

S.

Thanks everybody, expecially to Jakubi, for the tricks, it works perfectly!

S.

I see the html tags in my posts after I post it, and I don't know why...

 

 

Sorry for the code, I don't know what happened. Here there is the more readable version:

Good mornig, I've this expression:

diff(Q(theta, `ϕ`), `ϕ`, `ϕ`)+diff(S(theta, `ϕ`), `ϕ`, `ϕ`)+(diff(S(theta, `ϕ`), theta)+diff(Q(theta, `ϕ`), theta))*cos(theta)*sin(theta)+(4*M*G*k*(diff(Q(theta, `ϕ`), theta, theta))-4*M*G*k*S(theta, `ϕ`)+4*M*G*k*Q(theta, `ϕ`)-4*M*G*k*(diff(S(theta, `ϕ`), theta, theta))-(diff(S(theta, `ϕ`), theta, theta))-(diff(Q(theta, `ϕ`), theta, theta)))*sin(theta)^2

 

and I would order the factors in order to have all the factors with S(theta,phi) after (or before) ALL the factors with Q(theta,phi). I've tried with sort(..., Q(theta,phi)) but this seems not work on the derivative like diff(Q(...),theta) So, there is a metod to obtein this ordering? Or (better) to print this expression like two differential operator acting on S and Q? Thank you S.

Hi another thank you for the reply. I think that this worked for you because you don't have the definitions for the functions and operator. So I've charged the ws. It's here View 4492_secondo ordine2.mw on MapleNet or Download 4492_secondo ordine2.mw
View file details I've asked some questions on the worksheet Tk Salvatore

Hi, thank you for your rapid and useful help. I wish to ask you about innumerable questions! I've to use maple to study some asymptotic expansion for the Gauss-Codazzi eq. That is R[ijkm] = eta[A,B] (∇[i]∇[k] z^A ∇[j]∇[m] z^B - (A->B)) (I'm not sure that the maple tag work so I write the source: R[ijkm] = eta[A,B] (∇[i]∇[k] z^A ∇[j]∇[m] z^B - (A->B))) in which I consider expansion for the z^A functions, e for the Christoffel symbols (so Nabla also is an expansion) (eta is a high dimensional minkowski diagonal matrix, and is implicit the sum A=1..6, B=1..6) That I would is to isolate the term of the riemann tensor proportional to the several power of the expansion parameter. The problem is that if I let maple to do the explicit sum I've not a symbolic and compact answer because I can't "recognize" the summation terms (this will be excessively time expensive, nearly that do the calculus by hand!!!). On the other hand if I use the add command, maple don't expand the summation, and there is no simplifications!) Thank you for any help!!!! S.V.

Ok, I've created a init text file in /lib directory with the savelibname command, and it work proprely. Tk you! S.