## inert % does not obey order of operations...

4 %+ 3 %* 2;
%*(%+(4, 3), 2)

= (4+3)*2

It makes using % very difficult in complex expressions because one has to constantly use a ton of paranethesis just to get things to work out.

1 + 4%^3  %* 2 %- 6 %/ 4;

1 + ((((4 %^ 3) %* 2) %- 6) %/ 4)

= 1 + (4^3*2 - 6)/4

## pdsolve exception int/gbinthm/structure INVALID s...

I noticed number of pde's now fail in Maple 2021 with the error

int/gbinthm/structure INVALID subscript selector

but they do not fail in Maple 2020.2.

Here are few   examples

```restart;
pde :=a*x^n*diff(w(x,y),x) + n*x^m*y*diff(w(x,y),y) =s*x^p*y^q+d;
pdsolve(pde,w(x,y));

restart;
pde :=a*x^n*diff(w(x,y),x) + n*x^m*y*diff(w(x,y),y)=c*x^k*y^s+d;
pdsolve(pde,w(x,y))

restart;
pde :=a*x^n*diff(w(x,y),x)+b*x^m*y*diff(w(x,y),y) =  (c*x^k*y^s + d)*w(x,y);
pdsolve(pde,w(x,y))

restart;
pde :=  a*diff(w(x,y),x)+ y*diff(w(x,y),y) = b*w(x,y)+ c*x^n*y^m;
pdsolve(pde,w(x,y))

#etc..```

Error, (in int/gbinthm/structure) invalid subscript selector

While in Maple 2020.2 they all work. Screen shot

Maple 2021

Maple 2020.2

Any idea why this happens? Do others see the same error?

## n-dimensional metric in Physics package...

Hi!

How to define n-dimensional metric for arbitrary n in Physics package?

Thanks

## Derive the Euler Lagrange equations using field th...

I would like to compute the euler-lagrange equations using the index notation in quantum field theory. So for example given the Lagrangian here:

Is there a way to derive the Euler-Lagrange equation in maple?

## Maple 2021 / Problem while saving the workbook...

I've experienced problems a couple of times when trying to save a workbook in Maple 2021.

At first I thought it was due to a unstable VPN connection, but this also happens on a local drive.

## How to force Maple to express the derivatives of L...

Hi,

Consider the following example:

>> Maple express the second derivative of Legendre polynomial as

This form cannot, for instance, be integrated if we set n, for example, to 2.

i was wondering whether there is a trick to force Maple to express those derivatives in term of P_n using the relevent recurrence relations. This will help for further manipulations.

Thanks a lot!

Heinrich,

## Programming a loop for Trapezoid Rule evaluation o...

I have a 2688x1 matrix of ground acceleration data that I converted to a forcing function F (also a 2688x1 matrix) that I need to evaluate using duhamels integral. Since the forcing function can not be represented my a real expression numberical integration is required. Am needing to write a loop as seen on bottom of attached picture. Essentially to perform trapezoidal rule to return  structural motion (u).

Am looking for advice on how to write this loop in Maple.

I have attempted the for program in Maple per below with;

[F]:= Forcing Matrix
[t]:= time step matrix

Assigned initial conditions sim to pic below

for i from 1..2688 do

added the functions sim to bottom of pic for Ai, Bi, and ui

end do

## why the new documentation PDF's for Maple 2021 are...

This is just an obervation. May be due to me missing some clarification.

My understanding is that in Maple 2021, one can now export a complete Maple worksheet/document to Latex successfuly.

According to https://www.maplesoft.com/products/maple/new_features/  it says under "Latex export"

Export is available for individual expressions or the entire document, though the latex command

So I would have expected that now all the online PDF documents for the new features in Maple 2021 to be generated from Latex for better formatting.

But when going over number of documents, they do not appear to have converted to Latex before generating the PDF.

Even the PDF document about the new latex command does not appear to have been generated from Latex. I can quickly recognize a PDF that was generated from Latex, and these PDF files are clearly not.

Looking at sample PDF from Maple website, it says the generator is "iText" and not latex compiler.

It looks like these documents were just a direct export of the Maple worksheet to PDF, instead of being exporting to Latex first, and then compiled to PDF.

Am I missing something? Why not take advantage of the Maple Latex export, and convert all the documents to Latex first and then generate the PDF from Latex? This would make them look much better in terms of formatting and math rendering.

Here are some examples

Why did not Maple documentation take advantage of the new export command of Maple's latex command? This would also have been a good way and an opportunity to show case the effectiveness of the new latex export command.

May be it was not done due to time constraint before the release date of maple 2021? Or are there other technical reasons?

## How to draw a streamline by using stream function ...

How to draw a streamlines by using stream function provided in pdf. In the presence and absence of lambda parameter.

## Wht doesn't this work with Maple 13?...

This does not work with Maple 13. Can I still do something like this just using the linear operator D?

g:=x->x^(1/3);

f:=x->convert(g(x),surd);

D(f)(x)???

I need the derivative D(f)!!

Thank you!!!

mapleatha

## how to solve this problem...

Hi Mapke experts,Here is my try to solve the integration

int(x-t)^(-alpha)*a(t-bln(t+b/b),t from 0 to x)

I found it complicated to solve it symbolic, so \i try this:

restart:
assume(t,real):
x[0]:=0:a:=-0.1:alpha:=0.5:h:=0.001:b:=Gamma(2-alpha)/((1-alpha)*Gamma(1-alpha)):
for n from 0 to 0 do
t[n]:=n*h:
vo:=a*(x[n]-b*(ln((x[n]+b)/b))):
uo:=a*(t[n]-b*(ln((t[n]+b)/b))):
u1:=(int((x[n]-t[n])^(-alpha)*uo,t[n]=0..x[n])):
S[n]:=vo+u1:
od:

data:=[seq([t[n],S[n]],n=0..100)]:

## Sum of degree of neighborhs...

A function such that given a Graph G and vertex say v as input to a function

It should output the sum of the degrees of all the neighbors of that vertex v in that graph G

Kind help thank you

## Bug in Integration of square of Jacobi sine functi...

Dear all,

I believe there is a bug in integration of square of Jacobi sine function.

Here is what I did:

u := int(JacobiSN(x, k)^2, x);

The result I got is
x - EllipticE(JacobiSN(x, k), k)
u := --------------------------------
k^2
However, according to  Handbook of elliptic integrals for engineers and scientists by Byrd and Friedman Eq (310.02), it is supposed to be

x - EllipticE(JacobiAM(x, k), k)
u := --------------------------------
k^2

Note that I tried also to integrate first and third power of JacobiSN a the results are in agreement with the book.

## Help!. Trying to plot the series solution with the...

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