I am not sure whether this should be in "create a post" or "ask a question." Let me know if this is more appropriate in "ask a question"

The standing wave equation is given by:

PDE:=diff(u(x,t),t,t)=c^2*diff(u(x,t),x,x)

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}

pdsolve(PDE,IBC,numeric)

In my problem, the material is a magneto-elastic material where c, the speed of the acoustic wave, is a function of a magnetic field H.  The material is nonlinear and saturable.  I define it by a 3 segment piecewise nonlinear function of H.  The material response is a result of a sinusoidal H field.  I am interested in solving u(x,t).  

With that, c in the PDE has to be rewritten as c(H(t)), pdsolve gives an error as PDE has to be expressed as a function of u,t, or x.  So I redefine c(H(t)) as c(t).  I ran into another error in pdsolve as the piecewise has to be based on t or x and not H.  

The problem is that depending on H I can go through all 3 segments and back in one cycle and I have to find the corresponding t's for the piecewise.  Now I am driving the material with 100 cycles, I have to find and list all those piecewise transition points which is hardly practical.

Is there any other ways to approach and solve this problem?

Hello Friends.

I have used Maple to create a Polynomial Regression model.  The model is called "PRModel."  It works fine.  The independent variable is "X" and the dependent variable is "Y."  Both X and Y are of the vector variety.  The model is as follows:

PRModel:=PolynomialFit(10, X, Y, summarize = true);

I would like an estimate of Y for each value of X.  I would like the estimates of Y to be in a variable called "estY."   I have not been successful with this.  I have tried many different variations of the following, but have not been successful.  

estY := eval(PRModel, X);

Any suggestions as to how I can capture the estimates of Y? 

Thank you.

i recently noticed that i can no longer access maple transactions, usual link https://mapletransactions.org/index.php/maple/index automatically opens https://scholarsportal.info/, and in that web site, some pages do not open, stating

"The page you are trying to access is restricted to IP addresses from our member universities. Please try accessing this page from on-campus or through a VPN."

this seems like a geo ip restriction, i search for an announcement for this change but i couldn't any, could you please clarify situation?

thanks in advance..

On my journey of discovery through the Maple world, I now want to try out Maple's convenient features in the complex plane, something that used to be laboriously worked out and demonstrated on the blackboard with chalk. I couldn't find a suitable introduction in the help text. I'm interested in whether a package needs to be loaded and how to handle polynomials, series, and line integrals (I have a reasonable understanding only of the theory).

once i founded but  i lost the technique and i can't remember how i can reach the point how to find thus parameter and find the solution of pde

t1.mw

I just found a rather incredible error in versions 2025.1 and 2025.2.

The function works fine in version 2022.

The drag function in solve does not work, even for solving a very simple problem.

For example, in the equation 1 + 5x = 3x - 1, if I try to do 3x from right to left, a box opens with a good suggestion (subtract   1+2x = -1)

# subtract 3*x from both sides
((1)) + ~(3 * x)
we can see that the correct expression should be ((1)) - ~(3 * x)

I finally get:

1 + 8x = 6x -1 (it added and did not subtract 3x from both sides)

Please correct this...

I would like to plot multiple curves in a single graph with proper legends for different values of θ, similar to the sample figure. However, I am encountering an error while generating the legend. What modifications should I make to correct this? Additionally, how can I display labels such as θ=0.4, θ=0.5 etc., directly inside the plot as shown in the sample?

Graph_legend_error.mw

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

Mapleprimes issue

Trying to upload a mw file throws this error message

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