## error in Pde plot ...

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 > plotC := plots:-display(seq(Ans[k]:-plot(Bj[j], xi = 1, eta = 0 .. 10, color = colour[k]), k = 1 .. nops(lambdaVals)), linestyle = "solid", thickness = 2 );
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Help me to rectify the error

What is the mistake?

in this worksheet

## square matrices...

proc(U::Matrix);

 (1)

Hello! I've made these procedures but it doesn't result give me the result i want. Can someone please tell me where it is I made a mistake?

## How to program a dynamical loop?...

Hello

I have programs below for the cases n=3 and n=4. If n is increasing by 1, then there is one loop more. As you can see, that additional loop has always the structure:

x[i+1] from ceil(((n-2)*24-d[i])/(n-i)) to x[i]

whereas d[i] is the sum of the values of x before.

Now I want to write "nequaln":=proc(k), which goes through all the values for n from 3 to k and produces a list [a_3,a_4,a_5,...,a_n].

I guess that I need to program a kind of dynamical loop, but I failed completely. May someone help me? That would be very kind.

nequal3:=proc()
local u,v,a_3;
a_3:=0;
for u from ceil((3-2)*24/(3-0)) to (3-2)*24-3+1 do
for v from ceil(((3-2)*24-u)/(3-1)) to u do
if (3-2)*24-u-v>=1 then
a_3:=a_3+1;
end if;
end do;
end do;
print(a_3);
end proc:

nequal4:=proc()
local u,v,w,a_4;
a_4:=0;
for u from ceil((4-2)*24/(4-0)) to (4-2)*24-4+1 do
for v from ceil(((4-2)*24-u)/(4-1)) to u do
for w from ceil(((4-2)*24-u-v)/(4-2)) to v do
if (4-2)*24-u-v-w>=1 then
a_4:=a_4+1;
end if;
end do;
end do;
end do;
print(a_4);
end proc:

## How to efficiently find the length of some longest...

The old question "Longest distance in a graph via Maple code" offers some general methods to find longest paths in a given graph, while for directed acyclic graphs, the longest paths can be found much more directly via built-in functions. However, it apprears that even for small dags, Maple cannot solve this in an acceptable time. In the following example, I'd like to count the number of nodes that on longest paths for certain source and target vertexes.

 > restart;
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 (2)
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 memory used=7.99GiB, alloc change=0 bytes, cpu time=5.74m, real time=5.63m, gc time=22.55s
 (3)
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 memory used=4.34GiB, alloc change=32.00MiB, cpu time=3.26m, real time=3.19m, gc time=14.34s
 (4)
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Unfortunately, I have to wait for almost four minutes in the above instance. Can this task be done in 0.4s?

## MapleQuiz correct / incorrect how to make differen...

In the Grading Quiz, it is possible for students to indicate whether the answer is correct or incorrect. In the context menu, it is also possible to add an icon instead of the text.

For some reason, I can't get this to work! If I assign an icon to the correct answer, the same icon is transferred to the incorrect answer.

Is there a way that I'm missing that can show two different icons rather than the same one?

## How to prove this equality under given conditions?...

How to force Maple to prove equality (2) under conditions cond.

 > restart:
 > # Given #     0 < u < 1 #     0 < v < 1 #     theta > 1 # # let F the function defined by: F := (u, v) -> exp(-((-ln(u))^theta+(-ln(v))^theta)^(1/theta))
 (1)
 > # How to prove this equality for any n > 0? 'F(u^(1/n), v^(1/n))^n' = 'F(u, v)'
 (2)
 > cond := u > 0, u < 1, v > 0, v < 1, theta > 1, n > 1: simplify(F(u^(1/n), v^(1/n))^n - F(u, v)) assuming cond;
 (3)
 >

## How to export maple file to PDF on Linux correctly...

Hi, I am using ArchLinux and used Maple's official installer to install it. Whenever I export my Maple files as PDF all my "-" symbols are converted to "K" for some reason. Has anyone else had this issue or have an idea on how to fix it?

Below is a screenshot of what I mean. "-" has been replaced with "K"

## How to get revolution surface of polar coords curv...

Hi! Do you know how can I plot revolution of this curve:

plot(1 + 1/4*sin(8*(1 + 1/8*sin(16*(1 + 1/16*sin(32*t))))), t = 0 .. 2*Pi, coords = polar)

to get a wrinkled torus like this:

Do u have any idea? (I've tried to convert this polar curve to cartesian coords but I don't get it)

## Mapleflow map won't work with left quotes...

map won't work with left quotes

L:=[2,"foo",4]

## How to calculate the number of ways a number can ...

Hello

I have a list with n positive integer numbers and a positive integer k.

I would like to write a Malple programm, that calculates, in how many ways k can be written as a sum of numbers in the list.

Easy examles: let the list be [2,3,6,9].

k=9 can be written in 4 ways: 9=9, 9=6+3, 9=3+3+3, 9=3+2+2+2. The result therefore shoud be 4.

k=8 can be written in 3 ways: 8=6+2, 8=3+3+2, 8=2+2+2+2. The result therefore shoud be 3.

Thank you very much your help!

## MapleFlow for next loop...

I cannot get this to work:

Print all the non-string entries in a list:

 > L := [1, 2, "abc", "a", 7.0, infinity]:
 > for x in L do     if type(x, 'string') then         next;     end if;     print(x); end do;

## Generating class tests in Maple?...

Hi everyone,

I am using Maple for quite a while, now I would like to do something new.

I am a teacher at a german highschool and I would like to generate class tests with maple. Say for an example, I need 30 tests,  where the first task is calculating the first derivative of a function. This function should be different for every person, for example f(x)=a*x^3+3x^2, where the value of a is different in every test (probably random).

So what I need is a way to generate nice looking sheets in Maple (including page breaks, titles and so on). Is there a way to generate such a thing in maple or do I have to export to TeX and adjust there quite a bit?

Maybe someone has done a similar thing. Actually I am looking for something like serial letters in Maple.

Any idea, how I could do such a thing?

Axel

## GraphTheory['AllPairsDistance']: Which output is c...

`GraphTheory:-GraphEqual` says that G1 and G2 are equal, but `GraphTheory:-AllPairsDistance` gives different results instead:

 > restart;
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So, which one is incorrect? Any reasons?

## Is there any bug in the "randpoly" command?!!...

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 {--> enter randomzero, args = [x, y]
 <-- exit randomzero (now at top level) = [x^2-y-4, y^3-3*x]}
 (1)
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Hi

I think there is a bug in the "randpoly" command. please see the attached file line 7 of my procedure "randomzero". Why x^2-y-4 is created while terms=1 is considered and the outputs must contain binomial?

## Limitations of `sum`?...

Some work, while others don't work.

 > restart;
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