Maple 2020 Questions and Posts

These are Posts and Questions associated with the product, Maple 2020

I am trying to do the integration on the picture (int1). V,omega,theta,rhotræ,ix,iy,ixy,E,R are constants. a(r),å(r),FL(r),FD(r) are splines. It seems to run forever without any error. I have tried a simpler version to figure out if the problem has to do with the splines or the arctan. They can run independently but not when combined. (int2). I use an i7 6700k. I am fine with an aproximated answer within a couple %.  


How do I solve a equation ln in




When doing chemistry in Maple, I want to be able to do my calculations with units.

Maple does not support the unit [M] (molar concentration), so I have to manually type the unit as [mol/L].


That is not a problem in itself, but I have encountered som issues with Maple's own formatting of the units.

For example, in the attached document I want the output unit to be (mol/L)^(-2). However, Maple automatically formats it as (L^2)/(mol^2)

It even does the same thing in the "Maple Math" here on MaplePrimes - Here I try to type (mol/L)^(-2): (mol/L)^(-2)


So does anyone know a way to avoid Maple's auto-formatting of the output, or is there a way to customize it so I get my desired output?


I have attached the document with some screenshots in it:


// Frederik

I am investigating the history of scales and temperament in western music. I would like to be able to play a tone of a given frequency in Maple, and then a sequence of tones to make a scale, and then a collection of tones to make a chord. I found the Play command  in the online help screen for Audio Tools, but can't make it work. I don't get an error message, but neither do I get a sound. 

I have the following equations and plot in Maple, but I would like for Maple to only consider positive values of k, but I cannot find a way to do this as k is dependent on x. Is there any way to do this either in the code for k, or in the code for the plot?






Im having trouble fully opening the contents of my maple file. Only half of the doucment is showing up.

I get the following message: "There were problems during the loading process, Your worksheet may be incomplete."

There is also no bak. file available. 

Can anyone please help?


I was wondering if anyone had a solution for this issue, everytime I try to export my work as a .pdf file the program freezes up and I have to shut it off using task manager.

I have Maple 2020 installed in addition to Maple-Gym.

I've noticed after a creating a few documents that when save such documents as PDFs on my Mac, the drawing elements in my drawings are misalgined. Is this just a bug or is there a way to prevent this?  I've attached screenshots of the correct drawign in a document and what the result is in a pdf.

Dear Maple community,

I'm trying to calculate a Steady State Vector of the attached matrix using this Maple routine, but, unfortunately, don't get any solution even after a 30 min calculation on a 64Gb machine. Am I doing something wrong and, if so, could you please give me a hand how to conduct this calculation? Thanks!

Hello all,

at the beginning of my document I need to assign a value to my variable, for example 0.4, so I can calculate a number of material pararamters for this exact value. At the end I want to include a plot that demonstrates the material behaviour for the variable ranging from 0 to 1. 

However, I have found that I can not plot a graph if I have assigned a value to that variable before. The "unassign" command sadly does not work. 

I am a beginner in Maple so i am probably missing something obvious, but I would appreciate any help.

Thank you!


I have used Maple almost daily for the last four years, but a few days ago two students approached me with an issue I had never encountered before. However, it had happened to both of them within a few weeks.

They described the issue as follows: When they opened a random Maple document and they tried to type in simple operators (like +, - or *), Maple would instead write an odd symbol, which none of them recognised as a mathematical symbol.

As they could not find a way to solve the problem within Maple, they tried restarting their computers. When they afterwards reopened Maple, the problem was gone and the operators worked as expected again. Neither of the students has experienced the issue since.

During the last few days, I have been trying to replicate the issue myself without success. Therefore, I also don't have any screenshots to share, so hopefully my simple explanation is enough.

My questions are: Has anyone heard about this issue before? Does anyone know what might have caused it? Is there a way to replicate it and/or prevent it from happening again in the future?

I hope someone is able to clarify it a bit for me! :)



The changecoords command in the procedure below executes the plots:-changecoords command despite the preceding unwith(plots) command.

How can I execute the non-plot version of the changecoords command in the procedure. It would be very inconvenient of all the various commented plot commands had to be preceded by plots:-

restart; with(plots):   # first command in the worksheet

  # many statements executing various plot commands

P := proc()


changecoords([x, y, z], [x, y, z], spherical):


end proc:

Error, (in plots/changecoords) changecoords does not accept plot options or other additional arguments

  # many more statements executing various plot commands


 # last command in the worksheet

Dear Maple community,

I was wondering whether you could help me with the following problem: Consider the non-linear system of 4 equations in 4 unknowns: {y[2,1], y[2,2], y[4,1], y[4,2]}, see Please also note that equations y[2,1] and y[2,2] in sys2 are homogenous of degree 1 (i.e., defined only up to scale). In principle, it should be possible to choose either y[2,1] or y[2,2] as a free and unconstrained variable (a scaling factor) and express all other unknowns in terms of it. Unfortunately, I couldn't yet implement it in the current setting and was wondering whether you give me a hand. Thank you very much in advance!


sys1 := {y[4, 1] = 33^(2/3)*50^(1/3)/(33*(1/(y[2, 1]^(3/2)*y[4, 1]^(3/2)))^(1/3))+2^(2/3)*5^(1/3)/(2*(1/(y[2, 2]^(3/2)*y[4, 2]^(3/2)))^(1/3)), y[4, 2] = 11^(2/3)*50^(1/3)/(11*(1/(y[2, 1]^(3/2)*y[4, 1]^(3/2)))^(1/3))+4^(2/3)*5^(1/3)/(4*(1/(y[2, 2]^(3/2)*y[4, 2]^(3/2)))^(1/3))}

sys2 := {y[2, 1] = 33/(100*sqrt(y[2, 1])*y[4, 1]^(3/2)*(33/(50*y[2, 1]^(3/2)*y[4, 1]^(3/2))+2/(5*y[2, 2]^(3/2)*y[4, 2]^(3/2))))+11/(40*sqrt(y[2, 1])*y[4, 1]^(3/2)*(11/(20*y[2, 1]^(3/2)*y[4, 1]^(3/2))+1/(2*y[2, 2]^(3/2)*y[4, 2]^(3/2))))+3*y[2, 2]/(20*y[2, 1]^(3/2)*y[4, 1]^(3/2)*(11/(50*y[2, 1]^(3/2)*y[4, 1]^(3/2))+4/(5*y[2, 2]^(3/2)*y[4, 2]^(3/2))))+3*y[2, 2]/(10*y[2, 1]^(3/2)*y[4, 1]^(3/2)*(11/(25*y[2, 1]^(3/2)*y[4, 1]^(3/2))+3/(5*y[2, 2]^(3/2)*y[4, 2]^(3/2)))), y[2, 2] = 11*y[2, 1]/(75*y[2, 2]^(3/2)*y[4, 2]^(3/2)*(33/(50*y[2, 1]^(3/2)*y[4, 1]^(3/2))+2/(5*y[2, 2]^(3/2)*y[4, 2]^(3/2))))+11*y[2, 1]/(60*y[2, 2]^(3/2)*y[4, 2]^(3/2)*(11/(20*y[2, 1]^(3/2)*y[4, 1]^(3/2))+1/(2*y[2, 2]^(3/2)*y[4, 2]^(3/2))))+2/(5*sqrt(y[2, 2])*y[4, 2]^(3/2)*(11/(50*y[2, 1]^(3/2)*y[4, 1]^(3/2))+4/(5*y[2, 2]^(3/2)*y[4, 2]^(3/2))))+3/(10*sqrt(y[2, 2])*y[4, 2]^(3/2)*(11/(25*y[2, 1]^(3/2)*y[4, 1]^(3/2))+3/(5*y[2, 2]^(3/2)*y[4, 2]^(3/2))))}



Fortran 2000 introduced a simple system for interoperability with C. That was expanded in 2020 to provide C macros to support Fortran concepts that do not exist in C, such as optional arguments and assumed-shape arrays. This is all described in Chapter 18 of the Fortran 2020 standard at


I want to call Maple from Fortran. The StartMaple function has a result of type MKernelVector. I can't find any description of it in the Advanced Maple Programming Guide other than that it's a handle. In order to create a Fortran variable to hold the result of StartMaple, to pass to the other functions, I need to know more. Is it an int or a long or a longlong or a pointer, or what?


I guessed longlong would work, but it apparently doesn't. The result value of StartMaple is nonzero and apparently at least 64 bits. Invoking EvalMapleStatement using that result value causes a segmentationf fault (I'm running Debian Buster 10 Linux).


That's as far as I've gotten.


Any ideas how to proceed?


How Would I fix that?

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