These are the original set up to solve for second order partial differetial equations:

E := 1.456*10^11;
rho := 7900;
a := sqrt(E/rho);
L := 0.03639;

f0 := 1/(2*L)*a;
f := f0 - 50;
A0 := 11.75*L/2*10^(-6);

d := 0.8*1000;
T0 := 5/f;
NULL;
PDE := diff(u(x, t), t, t) = a^2*diff(u(x, t), x, x) - d*diff(u(x, t), t);
IBC := {u(x, 0) = A0*cos(Pi*x/L), D[1](u)(0, t) = 0, D[1](u)(L, t) = 0, D[2](u)(x, 0) = 0};
pds := pdsolve(PDE, IBC, numeric, timestep = 2*10^(-7));

 I know it solves properly because I can plot it using pds:-plot without problem.  The question is how to extract the value at specific x and t.  I started to try some of the more intuitive way such as u(0,0) without getting an answer.  I tried a number of eval expression such as eval(pds,[x=0,t=0]), eval(u(x,t),[x=0,t=0]) and so on without success.  

Then I tried using :-value as mentioned in an example from the internet, also resulting in an error.

val:=pds:-value(x=0,t=0)

It seems to be simple.  I guess I am too new with maple so be gentle.  Thank you.

Hi,

My student licence  expired yesterday mar1. According to the description of my student licence it renews automatically. So I did not get active. But apparently it did not occur automatically. When starting Maple I get the message that my licence expired yesterday. To check whether the automatic renewal applies but did not work or whether I have to purchase a new licence for the next 12 months I tried to contact the customer support through online form. 

I do not see any other channel to contact customer support by mail or phone, what can I do ?

Manfred

When I solve for Pr and q simultaneously using Maple, I obtain a solution that differs from my manual derivation. I suspect there may be an issue with the solve function or the way it is specified. Could anyone please suggest how this can be corrected?
Manually solving q* = (Cv-Cd+Ce*tau-Ci)/(4Cr-t) which is different from maple results.

Sheet:Question_1.mw

Hello Friends,

I have a function f(t) which I would like to convolve with itself.  I have no problem doing that typically, but my function contains two elliptic integrals (EllipticE and EllipticK), which clearly complicates matters.

My work in included.  As you can see, the plot on the (0,2) interval is continuous, and the area under the curve sums to unity via numerical integration.

Download CircleDerivation2.mw

Are there any sort of transformations that I can employ which will permit me to convole this function with itself?  I realize a closed-form solution is probably not likely, but something approaching closed-form would be nice.  Via simulation, I have learned that the self-convolved function will have a continuous boundary on the (0, 2*sqrt(2)) interval.

nans:=dsolve({(-y^4+y^2)*diff(U(y),y,y)+(-2*y^2+14.2)*diff(U(y),y)*y-15.2*U(y)*(U(y)-1)*(U(y)+1) = 0, DU(.99999) = -.3401375821,U(.99999)= 0.3000034013},numeric);
Error, (in dsolve/numeric/process_input) invalid specification of initial conditions, got DU(.99999) = -.3401375821

I use  

Typesetting:-Unsuppress('all'):
Typesetting:-Settings(prime=t,'typesetprime'=true):

to make the math easier to read. (also the latex looks better this way).

But it has no effect when on the plot title. Here is screen shot and code

In this below, I get same title if I use   plot(t,'title'=typeset(the_title));   or plot(t,'title'=the_title);  Instead of dy/dt,  I wanted it to show as y'(t) like it does in worksheet.

Is there a way to make the title of the plot show the math in the nicer format shown in the worksheet automatically? It looks like Typesetting:-Settings does not extend to plots, which is too bad.

code

the_title:=diff(y(t),t$2)+c*diff(y(t),t)+k*y(t)=0;
Typesetting:-Unsuppress('all'):
Typesetting:-Settings(prime=t,'typesetprime'=true): #this says to use y'(t) instead of dy/dt    

plot(t,'title'=typeset(the_title),size=[300,300]);

#or

plot(t,'title'=the_title,size=[300,300]);

Is this a Maple bug? I do not see what I am doing wrong:

Moving any slider gives the internal error.  Why?

Download internal_error_explore_feb_28_2026.mw

Here is a small movie

To help debug things, and to make it easier to add more logic such as if then else and so on, I moved the main body of Explor to a separate proc where the plot is made after doing some checking.

So instead of writing

Explore(plot(.....), 
 parameters=[  
   [c=0..10,....],
   [k=0..10,...]]
)

It now became

foo:=proc(c,k}
.....#some debug print messages added here, and some checking...
   plot(....)
end proc;

Explor( foo(c,k), 
  parameters=[  
    [c=0..10,....],
    [k=0..10,...]]
)

Two problems. 

1) My print lines inside foo() do not print to worksheet. Only the initial time they do. When I mean initial time, it is when Explore starts and does initalization. I see the print lines only then.

But after that, as I change the slider, which should make a call to foo(), I see nothing printed on the screen in my worksheet any more.

It is as if Explor stopped calling my foo().  But at same time, I see do see in the the display of Explore itself that it is calling foo as expected, since the call it display is changes and the result of the call changes as slider is changed. So call is being made. 

This is what shows inside Explore...

foo(5,2)=10
foo(3,2)=6
and so on

Why then the print messages from foo() are not printed in the worksheet any more? Where are the print message going to then?

2) How to make Explor only show the _result_ of calling foo() and not show the call itself as it does now? 

ie. instead of showing foo(5,2)=10  I just wanted to see the result of foo, which is 10 in this example.

Doing rhs(foo(c,k)) did not work

Here is worksheet to see yourself.

Download explore_feb_28_2026.mw

Here is small movie

ps. I am thinking now Explore only works with "plot" as its first argument. But help says expr can be anything.

Goal: to make a 3D parametric plot of a complex function u(x,t) obtained by pdsolve.  I tried to follow one example of a plot of a complex expression/function.  I was unable to get any plot.  I got some warning and error.  Please let me know what have I done wrong.

I follow this example so that I can get a 3D parametric plot of a complex function u(x,t) for a fix x:

with(plots);

complexplot(exp(t*I), t = 0 .. 2*Pi, scaling = constrained);

plot([cos(t), sin(t), t = 0 .. 2*Pi], scaling = constrained);

z := t -> exp(t*I);

spacecurve([Re(z(t)), Im(z(t)), t], t = 0 .. 4*Pi, axes = normal, labels = ["Re", "Im", "t"]);

It was successful.  With the following pde, I obtain an analytical solution using pdsolve.

a := 3;
L := 2*Pi;
d := 0.5;
T0 := 2*Pi;
PDE := diff(u(x, t), t, t) = a^2*diff(u(x, t), x, x) - d*diff(u(x, t), t);
IBC := u(x, 0) = cos(Pi*x/L), D[2](u)(x, 0) = 0, D[1](u)(0, t) = 0, D[1](u)(L, t) = 0;
pds := pdsolve({IBC, PDE}, u(x, t));

It fail 2D plotting using the following:

with(plots);
complexplot(u(0, t), t = 0 .. 6);

So I break down the pds with the following:

RP := Re(pds);
IP := Im(pds);
RP0 := eval(RP, x = 0);
RP0t := unapply(RP0, t);
IP0 := eval(IP, x = 0);
IP0t := unapply(IP0, t);

And I was hopeful as the following give me real numbers when I approximate them:

RP0t(1);
                             "(->)"

                     Re(u(0, 1)) = 0.20248

RP0t(2);
                             "(->)"

                     Re(u(0, 2)) = -0.57765

But it fails in both 2D and 3D plot:

plot([RP0t(t), t = 0 .. 6])

spacecurve([RP0t(t), IP0t(t), t], t = 0 .. 6, axes = normal)

Dear sir,

i want to draw velocity and temperature plots for fluid and dust phases. but getting error in that showing 12 BC need only 8 
i have tried with 8 Bc also but showing different error how to rectify it

dust_phase_work_error.mw 

I have two equations developed in different ways and I want to compare them.
The first is a development done using maple, while the second is an algebraic analysis.

I need to find out if both are identical and, therefore, if the subtraction would be equal to zero.

How should I proceed?

I had thought about simplifying the first and comparing it with the second; is that a good approach?

Download TESTE_MAPLE.mw

my question is a little bit long but is not complicated, i want find thus  unkown but  realy i am don't know how apply on it by maple, i have two best paper which explain very well i just want to find thus dimensional Lie algebra which is be invariant or not satisfy condition or not which i have to used or which i have not to use it also the importan part how find them in paper 1 first , for equation fisher 
How find eq(29) which is i think is two -dimensional Lie algebra of equation, also the best part is reduction which by apply this we can change PDE to ode but i don't know how apply eq(31) or even find it yet  is related to eq(27-28)  and by replacing equation eq(34) we can get our ode i am just loking for the ode, for the eq(76) and eq(85) have same procedures,  i will mention the paper link too 

Lie.mw

paper-1

paper-2

given

ode:=x^2*diff(y(x),x)+cos(2*y(x)) = 1; 
ic:=y(infinity) = 5/4*Pi; 
mysol:=cot(y(x))=2/x+1;

the above solution is verified against the ode, but Maple do not give zero for the IC part. It gives 

                                 [0, -Pi*_Z6 + Pi]

But we can see the IC are verified also

limit(eval(mysol,y(x)=5/4*Pi),x=infinity)

Gives

                                    1 = 1

my  code checks if the entry in the result of odetest is zero or not. Hence for -Pi*_Z6 + Pi it thinks now the solution is wrong because it is not zero.   Ofcourse looking at it on the screen, we see that for _Z6=1 then it becomes zero.  

The question, why Maple odetest do not return zero for the IC part?

eq:=cot(y)=-A;
solve(eq,y)

eq:=cot(y)=A;
solve(eq,y)

I would expect solution to first to be arccot(-A) and for second to be arccot(A) but Maple likes to write the solution for the first one as Pi-arccot(A).

Of course Maple solution is correct. But why make it so complicated? Why not just give arccot(-A) as solution?  A is just a symbol.

I tried 4 different cas systems and they all give arccot(-A) for first one, except Maple gives Pi-arccot(A)

Is there some subtle reason why Maple gives solution like this instead of the simpler one? 

And is there a way to tell Maple not to do this? This seems to be something hardcoded internally in its automatic trig simplifications? I just do not see the point of writing it this way. May be someone knows why.

How can I display numerical values alongside a plot as shown in the sample below? What is the syntax?

Q_legend.mw