Thomas Richard

Mr. Thomas Richard

2263 Reputation

12 Badges

11 years, 177 days
Maplesoft Europe GmbH
Technical professional in industry or government
Aachen, North Rhine-Westphalia, Germany

MaplePrimes Activity

These are replies submitted by Thomas Richard

@Al86 No idea, sorry, and no more time left this week.

@Al86 Checking the textbook formulae in your Maple worksheet is your job - I'm not going to do that, sorry.

But the eval statement at the end of my code snippet proves the incorrectness of the claimed equation.

@Al86 That cannot be correct in general, please check:

Delta := -2*M*r + a^2 + r^2;
rho := sqrt(r^2 + a^2*cos(theta)^2);
ES := (a^2*sin(theta)^2 - Delta^2)*((a^2 + r^2)^2 - a^2*Delta*sin(theta)^2)*sin(theta)^2/rho^4 - 4*a^2*M^2*r^2*sin(theta)^4/rho^4;
eqn := ES = -Delta*sin(theta)^2;

So there must be a typo or transcription error somewhere (I don't thave the book).

I'm seeing this with Maple 2020.2 on one of my Windows 10 machines, but only when the Maple session has been running for many days, and processed dozens of worksheets, with ~10 tabs opened in parallel. My guess is that something in the font cache gets scrambled, so it may be related to lower level routines (OS, Java, ...). Though I have been unable to reproduce this reliably, I'm still trying to pinpoint the problem.

What helps temporarily for me is zooming in with Ctrl + mouse wheel. Could you try on your machine?

@Preben Alsholm You must be eagle-eyed! I can hardly read anything on that screenshot. Yes, I know how to enlarge the bitmap graphics, but even then it makes no sense to use it for asking questions. I wish all new MaplePrimes users had to confirm that they understood this before their account gets enabled...

Please do not post screenshots - nobdody will type in anything from them. Upload your worksheet (mw file) instead, using the green arrow-up button of the message editor.

@subzero That is easy to import, though I haven't checked its correctness:

currentdir(cat(kernelopts(homedir),"/Documents/Mma/")); # set working directory where the txt file exists
line1 := op(readdata("PDE.txt",string));
cont1 := convert(line1,FromMma,'evaluate');
pde := op(cont1); # need to supply a r.h.s. as well here...

This might get you started. I have left semicolons in place so that you see the intermedate results. Replace them by colons as needed.

Sorry, I overlooked that your example contains two expressions in one line. Use

pde1 := cont1[1];

etc. to extract the individual PDEs.

@Harry Garst Okay, I see. By the way, you can also keep the Digits:=20 setting and additionally set UseHardwareFloats:=true before executing the problematic line.

@Harry Garst Thank you; we will investigate.

A first brief analysis indicates that the error is related to the Digits:=20 setting. Can you live with Digits:=15 or lower?

Please upload your worksheet so that we can reproduce the problem. Use the green arrow-up button in the message editor.

Both packages are designed to be compatible, of course, so this is an unexpected error message that we would like to fix.

MTM is an auxiliary package for the Maple Toolbox for MATLAB, so it's not meant to replace VectorCalculus in any way.

@Andreas Greuer You mentioned Maple 2021.0; so could you please install the 2021.1 update from here and try again?

@nm Evaluating at x=0 is needed because that‘s where the IC is given.

If you just supply ode as the 2nd argument to odetest, it will return 0 as expected. So it‘s the list [ode,ic] that makes trouble here. Therefore, I suggested to help odetest in evaluating the IC.

@Preben Alsholm There are more errors, e.g. thata vs theta in the spoke procedure.

Hint to @Rouben Rostamian: maplemint(<your proc name>) will detect that.

Also, I would not use short form of package commands in procedures - better insert uses plots, plottools: in all of them.


@Rouben Rostamian  The problem seems to be the derivative in the integrand - that case is not covered by intsolve routines, so it is being rejected (with an incorrect error message, though).

@Mariusz Iwaniuk We are grateful for feature suggestions, but please understand that we cannot give a public commitment about implementing non-trivial features in a certain timeframe (or version).

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