I have a list of relationships between variables, in this example there are three. The third of these requires at least one of the parameters to take a negative value i.e. kh[a1] = -kh[a2] how do I eliminate sets from a list like this that do that?


Sa1 := [{R = R, Rh = R, C[T] = Ch[T]*kh[a1]/k[a2], Ch[T] = Ch[T], k[a1] = kh[a2]*k[a2]/kh[a1], k[a2] = k[a2], k[d1] = k[d1], k[d2] = k[d2], kh[a1] = kh[a1], kh[a2] = kh[a2]}, {R = R, Rh = R, C[T] = C[T], Ch[T] = Ch[T], k[a1] = -(C[T]*k[a2]-Ch[T]*kh[a1]-Ch[T]*kh[a2])/C[T], k[a2] = k[a2], k[d1] = k[d1], k[d2] = k[d1], kh[a1] = kh[a1], kh[a2] = kh[a2]}, {R = R, Rh = Rh, C[T] = C[T], Ch[T] = Ch[T], k[a1] = -k[a2], k[a2] = k[a2], k[d1] = k[d1], k[d2] = k[d1], kh[a1] = -kh[a2], kh[a2] = kh[a2]}]

Hello!

I want to use abstract linear operators between Lie algebras. I have the problem shown in the following short code:

with(LinearAlgebra): with(DifferentialGeometry): with(LieAlgebras):
LAr:=LieAlgebraData([ [e1,e2]=e3],[e1,e2,e3],LA);
DGsetup(LAr);
define(lin,linear);
lin(-e3);
lin(-LieBracket(e1,e2));
lin(LieBracket(e2,e1));

As you see, the minus "-" does not come out of the argument of lin() in the last line. What is going wrong?

Thanks!

-------------------------------------

Later on, I realized that the linear operator has nothing to do with the issue. The problem lies in the fact that the output of "LieBracket(e2,e1)" is "_DG([["vector", LA, []], [[[3], -1]]])" , where the latter "-1" refers to the coeffiecient. For some reason, this coefficient is not handled in the way I would expect. For example, the following two lines:

LieBracket(e2,e1)+LieBracket(e1,e2);
_DG([["vector", LA, []], [[[3], 1]]])+_DG([["vector", LA, []], [[[3], -1]]]);

give both as an output "e3+-e3" instead of "0", while both the lines

LieBracket(e2,e1) + LieBracket(e2,e1);
_DG([["vector", LA, []], [[[3], -1]]])+_DG([["vector", LA, []], [[[3], -1]]]);

give the output "2-e3" (which I interpret as "2(-e3)" ).

I don't understand what I am doing wrong.

I have PDE i trying to solve the equation using series.

pdsolve(diff(u(x, y), x, x)+diff(u(x, y), y, y) = Pi, series, order = 2);

Give me: "Error, (in DifferentialAlgebra:-RosenfeldGroebner) unexpected occurrence of the non-rational constants {Pi} in the given input" ?

pdsolve(diff(u(x, y), x, x)+diff(u(x, y), y, y) =gamma, series, order = 2);#gamma = 0.5772156649,Gives ERROR ?

If I  change instead of Pi is e or exp(1) works fine.

pdsolve(diff(u(x, y), x, x)+diff(u(x, y), y, y) = exp(1), series, order = 2);#OK.

It's a bug, design or  something else ?

Goodday sirs, 

            How can I get over these error message123.mw
 

Anyone with useful informations please.

Thanking you in anticipation for a favurabke response

Download 123.mw

pde := [diff(u(x, y), x, x)+diff(u(x, y), y, y) = 2*Pi*(2*Pi*y^2-2*Pi*y-1)*exp(Pi*y*(1-y))*sin(Pi*x), u(0, y) = sin(Pi*y), u(1, y) = exp(Pi)*sin(Pi*y), u(x, 2) = exp(-2*Pi)*sin(Pi*x), u(x, 0) = u(x, 1)]pdsolve(pde)

pdsolve(pde)

it does not return any solution and answer, kindly help.

Hi, 

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Here's the same issue (unanswered) way back in 2015 https://www.mapleprimes.com/questions/203811-DocumentTools-Retrieve-Function-Returns

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I appreciate any help you can provide.

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See example in attachment

Thanks

Hi all

I wnat to produce following matrix P_{2r+1, 2r+1} in maple.

can any one help me please?

Error, (in dsolve/numeric/process_input) system must be entered as a set/list of expressions/equations
moadele_asli2.mw

solve does not show result!!

dtm.mw

can i have step by step procedure of the solution of the follwoing problem

sys[1] := [-(diff(u(x, t), t, t))-(diff(u(x, t), x, x))+u(x, t) = 2*exp(-t)*(x-(1/2)*x^2+(1/2)*t-1), u(x, 0) = x^2-2*x, u(x, 1) = u(x, 1/2)+((1/2)*x^2-x)*exp(-1)-((3/4)*x^2-(3/2)*x)*exp(-1/2), u(0, t) = 0, eval(diff(u(x, t), x), x = 1) = 0]