Items tagged with syntax

Hi guys, I'm currently having a lot of trouble with Maple and can't seem to get stuff to work. I have the task of solving and modelling the Klien Gordon equation, with a chosen potential. The equation I'm trying to solve is:

> KGE := diff(psi(x, t), x, x)-(diff(psi(x, t), t, t))-12*psi(x, t)^5+10*psi(x, t)^4+6*psi(x, t)^3-3*psi(x, t)^2-psi(x, t) = 0   

I'm doing this by changing the pde into an ode via a transformation 

>tr := {t = tau, x = c*tau+z, psi(x, t) = U(z)}

>ode1 := dchange(tr, KGE, [z, tau, U(z)])

 >ode1 := collect(ode1, diff(U(z), z, z))

>c := 1/4

>ode2 := subs({U(z) = U, diff(U(z), z, z) = V(U)*(diff(V(U), U))}, ode1)

>sol := dsolve({ode2, V(0) = 0}, V(U))

>sol1:= sol[2]

>z := -c*t+x = int(1/rhs(sol2), U)

>solwave := psi(x, t) = solve(z, U)

 

I then checked if my solution, solwave actually solved the pde via pdetest(solwave,KGE) and it did. Hence this is what I took as one of the kinks. Although the kink solution looks hideous and I have no idea how to try and take the limit as x goes to infinity, as to show it tends to a vacuum of the potential. I've tried taking the limit but all Maple does is replace all the x with infinity signs... 

I then tried animating it to see if it worked, but it just looks wrong, there are breaks within the curve and also very random spikes which I cannot explain at all.. 

I tried this code exactly for the Sine Gordon equation and it works perfectly, it just all goes wrong when I try to change the potential. 

Here is a picture of the frame: 

as you can see it has spikes.. and breaks in the curve as well

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

Another issue I had was with dealing with the potential on it's own, every time I try inputting  

>1/2(u^2)(1-u)^2(1+2u)^2  

into maple it changes the expression into something completely different and wrong, it somehow comes out with an exponential of 8.. This is what I get:

(1/2)*(u(1-u))(1+2*u)^8

 

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

 

I also have a problem integrating, I try and plug in a value, i.e. 

>int(1/(x(1-x))(1+2*x), x)

but all this does is show me what I inputted but with a integral sign...

I'm very very new to Maple and have spent over a week doing this, but it just isn't working out at all :( Please help!! 

Hello, 

I look for a maple function / or a piece of code which enable to do repeated substitutions. In other words, repeat substitutions until there is no more possible substitution.

How can I do to make repeated substitutions ?

Here a example I would like to solve with maple

Equation on which I would like to conduct variables changements: 

Code:
eq := sin(psi[1](t)+gamma0(t))*cf+sin(gamma0(t)+theta[1](t)+psi[1](t))*mf-sin(gamma0(t))*hf-cos(gamma0(t))*lf+xp[1](t) = sin(psi[2](t)+gamma0(t))*cf+sin(gamma0(t)+theta[2](t)+psi[2](t))*mf-sin(gamma0(t))*hf-cos(gamma0(t))*lf+xp[2](t)


Definition of variables changement :

Code:
ChgtVariables:=psi[1](t)=Psi[1](t) - theta[1](t) + gamma[1](t),psi[2](t)=Psi[2](t) - theta[2](t) + gamma[2](t);psi[3](t)=Psi[3](t) - theta[3](t) + gamma[3](t),psi[4](t)=Psi[4](t) - theta[4](t) + gamma[4](t),theta[1](t)=Theta[1](t)+gamma[1](t),theta[2](t)=Theta[2](t)+gamma[2](t),theta[3](t)=Theta[3](t)+gamma[3](t),theta[4](t)=Theta[4](t)+gamma[4](t);


Application of subs function:

Code:
subs(ChgtVariables,eq);

The problem is that only one step of substitutions is conducted.

Here the expected result :

(sin(theta[1](t))-theta[2](t))*cf - (sin(gamma[1](t)-sin(gamma[2](t)))*mf  + xp[2](t) - xp[1](t) = 0

Thanks a lot for your hemp

Here is my Maple 16 code:

 I expected to get outuput

a [a,b,c]

a [a,c,b]

But I get no output.

Why?

 

 

 

Hi,

I'm trying to fill an Array but I don't know the correct syntax, and Maple help isn't much use.

How do I form an Array, A, which has 10 rows and 2 columns. Where one column is say the row number squared and the other column is the row number cubed. 

So A would be:

[1 1]
[4 8]
[9 27] .....

Also, I'm using the square and cube numbers as an example. But is there a general format for doing this, whatever the values I want to put in the array are?

Thanks


Why does "eval(c, [b=1,l=1])" turn out to be "1" not "1/1+x"??? its driving me cracy. THX

restart

 

a:=(1/(1+x/l))

1/(1+x/l)

(1)

eval(a, [l=1])

1/(1+x)

(2)

eval(a, [x=2,l=1])

1/3

(3)

c:=(1/b(1+x/l))

1/b(1+x/l)

(4)

eval(c, [b=1,l=1])

1

(5)

 



 

I have:

r:=t-><4cos2t+4sint,5cos3t+4cost,(sin3t+2sint)^2>

with(plots):

 

then I tried:

spacecurve(r(t), t = 0 .. 2*Pi, thickness = 2, color = black, axes = normal, labels = [x, y, z], numpoints = 150)

But I keep getting the error: Warning, unable to evalute the function to numeric values in the region. 

But I thought <4cos2t+4sint, 5cos3t+4cost, (sin3t+2sint)^2> was defined on the region t=0 to 2Pi??? 

I'm using Maple 2015 if that helps. 

Iam a newbie, just two weeks into my 30-days trial. I have been exploring the symmetry aspect of PDEtools, gone through materials in the help section but still having problem in some of my analysis. The answer to the titled question "Symmetry analysis with parameters" was really helpful but did not work out for me when the parameters are more than one. Attached is a sample question.

sample_question.mw

 


 

Download inf2.mw

hello

 

i write this set of differential equation in maple and get the following error?

Can anyon help me with this?

 

thanks

 

 

I've got this huge chunk of code which leads to an optimiazation at the very last line (Bestangles:=minimize(maximize()-minimize))). This minization is taking a very long time (havent solved it yet) and I would very much like to reduce that time. As I've understood maple does optimization by differentiating and then finding all extremes and comparing. Would this mean that since I minimize and optimize within a minimization command, it differentiates a ton of times? And if this is the case, can I somehow do the differentiation beforehand, since it is the same function being differentiate all the time? Or is there some other way I can improve the code? 
Thanks alot!

Heres the full code:

So I am trying to apply the Optimization function to a rather complicated problem I am currently working on, and having some trouble getting maple to cooporate. This is the part of the code that is giving me the error, with error included. All of the variables imputtet when calling OptimizeSpring are constants. If there is any other details I should add, please say so and I will add them promptly :) Thanks alot!
Maple problem

I suspect that it might be related to this suggestion, but I am not sure how to apply it http://www.mapleprimes.com/posts/95113-Optimization-Workaround-For-Operator-Form

I would like to plot the following singular double integral, but I cannot due to singularities...

 

where x>0, t=0.2 and m=0.2.

I defined f(y) function as f:=y->exp(-(y-4.68)^2/0.4):

I attached my file:
1st_try.mw

Thank you !

There is an error in my implementation as follow:

"Error, (in unknown) incorrect syntax in parse: `*` unexpected (near 1st character of parsed string)"

What I have to do to remove this error?

Tried different ways to apply unapply but failed:

a := .1994;

modfit3 := a*x^1.5;
 
f := unapply(rhs(modfit3), x);
%;
Error, invalid input: rhs received .1994*x^1.5, which is not valid for its 1st argument, expr

What's wrong here?

S

 

Hello,

I'm having some issues with this procedure it seems to take a very long time to evaluate. There is also an error in the Histogram I can't seem to fix... Does anybody know why? Any help would be greatly appreciated! Thank you in advance!

Kind regards,

Gambia man

Last_part2.mw

Hello I am trying to plot this differential equation,  have not had any success can any one help me.


plot(q(t)= Ce^-1/2 + sin2t +cos4t)

not sure what i am doing wrong and i just used the plot command

Thanks

2 3 4 5 6 7 8 Page 4 of 9