Hello Everyone,

First of all I want to thank you to pay attention to my post.

For some reasons I want to know when does the root of my solution is equal to 0 isolating α, which yields the following equation
 

When I substitute 1/2 it verifies the equation, but when I substitute other solutions my equation is not verified. For instance substituting "α=-1/l" I get something different from 0 as you can see

This code used to work OK in an earlier version of Maple 2018. I do not know what changed and if it some change in Physics package that caused it.

restart;
pde:=diff(u(r,theta),r$2)+1/r*diff(u(r,theta),r)+1/r^2*diff(u(r,theta),theta$2)=0;
bc:=u(r,0)=0,u(r,Pi)=0,u(0,theta)=0,u(1,theta)=f(theta);
sol:=pdsolve([pde,bc],u(r,theta),HINT = boundedseries(r = 0));

Now it gives the error 

Error, (in assuming) when calling 'assume'. Received: 'invalid arguments'

Workaround is to remove the HINT above. So the following now works

restart;
pde:=diff(u(r,theta),r$2)+1/r*diff(u(r,theta),r)+1/r^2*diff(u(r,theta),theta$2)=0;
bc:=u(r,0)=0,u(r,Pi)=0,u(0,theta)=0,u(1,theta)=f(theta);
sol:=pdsolve([pde,bc],u(r,theta));

Should this error message show up when using the HINT option?

Maple 2018.2 with Physics package cloud version 205.

Here is screen shot showing it was working in Physics 170

From time to time, people ask me about visualizing knots in Maple. There's no formal "Knot Theory" package in Maple per se, but it is certainly possible to generate many different knots using a couple of simple commands. The following shows various examples of knots visualized using the plots:-tubeplot and algcurves:-plot_knot commands.

The unknot can be defined by the following parametric equations:

x=sin(t)

y=cos(t)

z=0

The trefoil knot can be defined by the following parametric equations:

x = sin(t) + 2*sin(2*t)

y = cos(t) + 2*sin(2*t)

z = sin(3*t)

The figure-eight can be defined by the following parametric equations:

x = (2 + cos(2*t)) * cos(3*t)

y = (2 + cos(2*t)) * sin(3*t)

z = sin(4*t)

The Lissajous knot can be defined by the following parametric equations:

Where n[x], n[y], and n[z] are integers and the phase shifts phi[x], phi[y], and phi[z] are any real numbers.
The 8 21 knot ( n[x] = 3, n[y] = 4, and n[z] = 7) appears as follows:
 

A star knot can be defined by using the following polynomial:
 

By switching x and y, different visualizations can be generated:

Please feel free to add more of your favourite knot visualizations in the comments below!

You can interact with the examples or download a copy of these examples from the MapleCloud here: https://maple.cloud/app/5654426890010624/Examples+of+Knots

How can I calculate the Euler-Lagrange equation from the Lagrangian density from Gauged Baby Skyrme model in maple using the physics package? Here, the rules of the operation in the inner space are the same that of the vectors conventional: dot and cross products, etc...
Following below the Lagrangian density.

Errata:

Hello everyone!
Can you help me with my problem?
How can I automatically paste parts of denominator from one equations to another? Now I must do this manualy. Example of my problem is in file2.

File_2.mw

I have a question about Hilbert Series of the quotient of an algebra by a non-homogenous ideal. 

In maple help: https://www.maplesoft.com/support/help/maple/view.aspx?path=Groebner%2FHilbertSeries, it is said that 

The algorithms for HilbertSeries and HilbertPolynomial use the leading monomials of a total degree Groebner basis for J. Here J is an ideal.

I checked the following example. Let 

J:= [(x[2]-x[1])*(x[2]-x[3]), (x[4]-x[1])*(-x[5]+x[4]), (x[4]-x[2])*(x[4]-x[6]), (-x[3]+x[5])*(x[5]-x[6]), x[1]^3-1, x[2]^3-1, x[3]^3-1, x[4]^3-1, x[5]^3-1, x[6]^3-1];

and

t1:=map(LeadingMonomial, l, grlex(x[1], x[2], x[3], x[4], x[5], x[6], x[7], x[8], x[9], x[10], x[11], x[12]));

Then t1 is the ideal generated by the following monomials.
t1 := [x[1]*x[2], x[1]*x[4], x[2]*x[4], x[3]*x[5], x[1]^3, x[2]^3, x[3]^3, x[4]^3, x[5]^3, x[6]^3]

Using the commands:

l2:={x[1],x[2],x[3],x[4],x[5],x[6],x[7],x[8],x[9],x[10],x[11],x[12]};

factor(HilbertSeries(J, l2, t));

factor(HilbertSeries(t1, l2, t));

We obtain Hilbert(J,t)=(t^2+t+1)*(5*t^4+11*t^3+11*t^2+5*t+1)
Hilbert(t1, t) = (t^2+t+1)*(3*t^2+3*t+1)*(2*t^2+2*t+1)

These two polynomials are not equal. How does maple compute Hilbert Series for the quotient of an algebra by a non-homogenous ideal? Thank you very much.

Is there any way to integrate this in maple?

lambda^2*t*(diff(theta(t), t, t)) = lambda^2*(diff(theta(t), t))-Pr*s*lambda*(diff(theta(t), t))+Pr*(diff(theta(t), t))-Pr*t*(diff(theta(t), t))

If I used factor, it didn't simplify to 0. As you may notice that this value should be 0.

Never really used the writeto command but what's with all the typesetting gobbledygook in the text file?  It occurs with document and worksheet mode.  Perhaps it's only meant for classic or command line maple?

Is there a way to log the terminal output to a .txt file?

Dear all

Trying to plot this expresion

f := epsilon-1.5+9.3*I = (a+I*b)*(26.+I*(-45.-1.0*Re(a+I*b)^2-1.0*Im(a+I*b)^2))

implicitplot (a^2+b^2) against epsilon

many thanks

I am trying to solve a linear system involving large number of equations with constant coefficients using Solve command from the LinearAlgebra package. The maple program is giving solutions for a smaller number of equations (T=10,Ne=20,Ng=15). But if I increase the number of equations to (T=20,Ne=30, Ng=25), then I got the error kernel connection has been lost. I need to increase the number of equations beyond this also. Any help to simplify the code or finding errors is appreciated.

solntosystem.mw

I would like to perform an implicit differentiation of the following:

eqn := 5*(x*y)^2+x/sqrt(y) = x^2+2*(3*x^3+y^2)^3

However implicitdiff(eqn, x, y); produces an output that expands the result.  Is there a way to not have it expand?

I tried something to the effect of...

eqn := 5*(x*y(x))^2+x/sqrt(y(x)) = x^2+2*(3*x^3+y(x)^2)^3;

diff(eqn, x);

but now what I need to to isolate d/dx y(x)...

Any suggestions are much appreciated.

 my question is
I am working on for loop and there are multi-line inside it and I only need to show a specific result, not all that occurs inside the loop . is there any commend to do that in maple?

with(Statistics):

LetList := [C, E, F, H, K, P, T, W, X, Y]; LetList[Sample()];
           LetList := [C, E, F, H, K, P, T, W, X, Y]
Error, invalid input: no implementation of Sample matches the arguments in call, 'Sample:-ModuleApply()'

Can any one help me with random sampling from LetList ?

Melvin