Thomas Richard

Mr. Thomas Richard

2633 Reputation

12 Badges

12 years, 159 days
Maplesoft Europe GmbH
Technical professional in industry or government
Aachen, North Rhine-Westphalia, Germany

MaplePrimes Activity

These are replies submitted by Thomas Richard

@sand15 I'm not a developer, so not 100% sure what's going on here, but it turns out that your first conversion works if you formulate the piecewise with strict inequalities:

piecewise(And(x(t) > d-a, x(t) < d+a), 1, 0)

The help file (?convert,Heaviside) indicates that proper conversion is not always possible...

@acer It's easier to supply a filename directly, as opposed to a string variable. This is unfortunately a bit obscured in the ?CodeGenerationOptions help text (generic help document for all twelve target languages).

@Rashmi Uniyal Sorry, I don't have Maple 12 to cross-check, it is almost 14 years old. Perhaps the tilde operator was implemented later; in that case you can try


A list of two zeros confirms that the solutions are valid. If it still emits any error, you will need to manually check the solutions. Or better upgrade to a current Maple version. :-)

MaplePrimes is probably not the right place to discuss purchasing and policies.
When you joined the Maple Ambassador program, you should have gotten a specialized e-mail address - please use that.

Thank you!

Why are you using the dot operator here?

And even when replacing all dots by * signs, the expression for ans is syntactically incorrect. Please fix your input or upload your worksheet. Then we should be able to address your questions.

This is covered by the Units[Simple] package. Is that an option for you, or do you need Units[Standard] (mandatory)?

@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?

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