C_R

3887 Reputation

21 Badges

6 years, 305 days

MaplePrimes Activity


These are questions asked by C_R

I am pretty new to pdsolve.

?pdsolve/numeric states

PDEsys - single or set or list of time-dependent partial differential equations in two independent variables

This could be interpreted in a way that problems with 3 independent variables can be handled (time + two others).

The rest of the helppage only describes two independent variables and does not mention time.

In case the above interpretation is wrong, I have two questions:

  • If only two independent variables can be treated, why is time-depencency mentioned at all?
  • Is it possible to integrate the PDE of an axially heated rod of finite length and radius with the help of pdsolve where on one end of the rod a heat flux q=q(r) is applied?

Any links to similar problems solved with Maple (not necessary with pdsolve) are very much appreciated.

Edit: Updated BCs

PDE := diff(T(r, z, t), t) = alpha*(diff(T(r, z, t), r, r)+(diff(T(r, z, t), r))/r+diff(T(r, z, t), z, z))

diff(T(r, z, t), t) = alpha*(diff(diff(T(r, z, t), r), r)+(diff(T(r, z, t), r))/r+diff(diff(T(r, z, t), z), z))

(1)

Updated BC

BC1 := -k*(D[2](T))(r, 0, t) = q; BC2 := (D[2](T))(r, L, t) = 0; BC3 := (D[1](T))(R, z, t) = 0; BC4 := (D[1](T))(0, z, t) = 0; IC := T(r, z, 0) = 0

T(r, z, 0) = 0

(2)

NULL

Corrected original BC (this is a different case of constant external temperature)

BC1 := -k*(D[2](T))(r, 0, t) = q; BC2 := T(r, L, t) = 0; BC3 := T(R, z, t) = 0; BC4 := (D[1](T))(0, z, t) = 0; IC := T(r, z, 0) = 0

T(r, z, 0) = 0

(3)

NULL

Download 2d_BVP.mw

This is about avoiding that automatic simplifcation removes a factor of "1" before a unit.

Example output with removed factors:

Readers of technical notes not familar with Maple interprete the above missing values before units as layout errors.
Also reading it (e.g. with a screen reader) sounds strange: "m_l equals kg" or "m_1 of kg".  As a work around a float one (i.e.: 1.) can be used, which in some instances does not look as nice as

To improve the above I thought of an inert "1" or an inert multiplication that could be removed by the value command in subsequent calculations (not necessarily visible in a document to the reader when the input is hidden).
I could not find a way for an inert "1". With inert multiplication using %* a grey asterix is printed

Can we make the grey multiplication symbol invisble?

Related discussion on 0 mm and 1 mm

https://www.mapleprimes.com/questions/241946-Round-With-Units#answer313597

Maple 2026 print layout

PDF created with print -> Adobe pdf printer -> save to file

Is that related to the attached worksheet or my installation?
If that is not reproducible on other installations, can I someone provide a file that prints correctly to test my installation?

Anything I can do about the mixed up fonts?

pdf_print.mw

Other question: Where is the pagesetup in Maple 2026? Maple shows in the printlayout a pagebreak at about 80% of the displayed page. AI could not tell me

(edit) where the page setup is to adjust the page size.

In 2-D Math input:
In a product of more than two factors space is not allways sufficient to delimite factors when one of the factors is of type numeric.

Just for my interest: Is there a reason or a rule for that?

2-D Math: space interpreted as multiplication

a*b*c

a*b*c

(1)

2*b*c

2*b*c

(2)

With numbers this does not work in these cases

"a 2 c"

Error, missing operation

"a 2 c"

 

"a b 2"

Error, missing operation

"a b 2"

 

Multiplication operators are required

"2 2 c"

 

2*a*c

2*a*c

(3)

2*a*b

2*a*b

(4)

NULL

Download Missing_operation.mw

Has anybody seen something like that? I do not use Maple 2026 very often.

Does this vanish when the document is executed on another machine?

 

repeated_equation_labels.mw

Update:

  • expanding the document block by "show command" makes the equation labels disappear.
  • copying the input to another document block seems to fix the problem
1 2 3 4 5 6 7 Last Page 1 of 54