I have a degree in Mathematics and Physics from the Danish University Aarhus, comparable to a masters degree with thesis - majoring in Mathematics. In 1991-92 I was a visting scholar at UCLA, Los Angeles, following graduate courses in Applied Mathematics. Since 1992 I have been a teacher in a high school (gymnasium) in Denmark. Special interests: Applied mathematics, graphics and popularizing Mathematics.

MaplePrimes Activity

These are replies submitted by erik10

@Rouben Rostamian  Thank you. I appreciate it! I have testet your procedure and it works. What I would like, though, is having the Matrix creation done outside of the procedure. The problem is, that your script won't be able to automatically detect the size of the Matrix needed in order to display the entire Matrix. Here is my requirements: 

The user should specify the number of columns towards the top of the document, for example columns:=20. A procedure like your Do_Danish should give as output a list of symbols representing the original text stripped for all symbols and spaces except for the letters a-z, æ, ø, å AND the corresponding capital letters A-Z, Æ, Ø, Å. When that is done, the length of the list can be determined in order to calculate how many rows (variable named rows) are needed to display the 'strippedlist' as a matrix. Since Maple doesn't display an entire big Matrix by default, it will also be necessary to call the interface command to set it properly. I am thinking of something like:

textlength := Length(strippedlist);
rows := iquo(textlength, columns);
interface(rtablesize = max(rows, columns));

Then later use the following command to display the Matrix:

Matrix(rows + 1, columns, strippedlist)

I hope that makes sense? 

Thanks! I learned a few tricks from both of you. I prefer a Matrix containing the letters without quotes, because the quotes are too distracting to look at. I liked the commands iquo and irem and Explode, which I didn't know about. 

N doesn't need to be a multiplum of n, så in the last row there will often be some "empty" entrances. I don't know at the moment if I want displayed empty strings or zeros there. 

By the way: When using the 26 English letters the command IsLower works perfectly, but how do I handle it when I am dealing with the Danish Alphabet containing the three additional letters æ, ø and å at the end - summing up to 29 possible letters? 


@acer OK thanks a lot. Can you explain what makes it work more smoothly compared to the previous version? I like the wider slider bar! 

Sometimes I have wondered why it requires so much empty (white) space to the side, when using the Explore command. I wish there were ways to control it better ...

Erik V.

@acer Wow, and thanks for your reply. I was about to answer your first question when I realised you changed it. For a fixed value of T I would use the command shadebetween, but did not know how to make it work with a slider (Explore command). I did not expect it to be possible to add the rainbow colors. Your first option display the true colors from violet to red. I actually like that the y-axis is scaled when changing the T value. The y-values (intensities) are increasing quite a lot with temperature ...

I will have a more detailed look at code soon ...

For now thanks a lot!!

Erik V.

@Anthrazit I agree. An output of Maple should be readable for a person not using maple. An obvious choice could be pdf! Unfortunately it does not work very well. Not only are sizes of the graphs exaggerated in comparison to the text & math, line drawings, etc. on graphs are even completely removed from the image. Because of this, students may miss grades! 

Try to export the attached Maple file to pdf! The student have made a lot of effort into creating a figure in her paper. It just disappeared in her output. Why!


Tegn trekant ABC i et koordinatsystem, og tegn trekantens 3 medianer.




plot([-2, 4, 4], [1, 3, -1], style = point, gridlines)







@nm Hi nm

The rules are how the Government rules, so to say! All students have to upload their papers in pdf format. It makes good sense, when you are doing things digitally, because it means that everything stays fixed, whatever it is: language, math, biology, etc.. Beside: Not every censor is using Maple. Texas, GeoGebra and other systems are being used. 

LATEX is fine, but something for the classes after high school.

Kind regards,


@Kitonum  Thank you! Good idea to first realize that s different from t means s = -t. Then it reduces to a problem with one parameter only in the current situation. And better with k instead of _Zn. Also an ingenious geometric display of solutions! 

An additional question, when confronted with similar system of equations of two variables, where it might not be possible easily to use ad hoc arguments to reduce the equations: Is there a more general way to solve these kind of equations involving trigonometric functions numerically in given intervals? I was looking at the command Roots from the package Student[Calculus1]. It works for one equation with one variable, but it seems not to work for 2 equations ...



@Carl Love WOW! Very fast indeed. Although I do not need the speed in my current situation, it is goog to know for future operations ...


@mmcdara Thanks a lot! The code is indeed short, and it seems fast. I really appreciate your effort!



Thanks Thomas Richard and tomleslie

My file path doesn't contain special International characters (just English). It is strange, because I can open the file in all of the other versions 2019, 2018, 2017, but not 2020. I really hope it has to do with an issue in version 2020 and can be resolved in Maple 2020.1. Else it will be a definite problem, for me and for my students (if they experince the same problem). I just wonder why it works in the recent versions and not in 2020?



Big thanks to both of you.

Carl Love: I didn't know about using the sprintf command in connection with the textplot commnd. Works perfectly! 

Kitonum: Very illustrative! The animation will clearly show how the points are created one by one, using the golden angle. It also gave me the idea to add an animated gif to my webpage. 

My original idea was to somehow paint the solidcircles with different colors in order to more clearly illustrate the spirals going in one direction and the other spirals going in the opposite direction. I guess this is not easy in one figure, because every solidcircle needs both colors then. Another way could be to first create a figure showing the spirals going in positive direction by applying one color to every second spiral and another color for the spirals going in negative direction. Similar for a second figure displaying the spirals going in negative direction. From the numbering I can now identify the points on the indidual spirals. Not surprisingly the difference in numbering is 34 and 55 (Fibonacci Numbers!) for points on either kind of spiral. I will look into that. 

I wish you a happy New Year!

@mmcdara Thanks to both of you. I think the ColumnGraph is the appropriate command here, because I am not going to produce a Histogram by having something counted. I have the height of the columns already. Your file was however valuable afterall, mmcdara! I have tried writing the appropriate command for my easy purpose (see attached file).  I am however surprised that it cannot be done in a more easy default way - if that is the case. I have to fiddle with an offset option. I was expecting Maple to be able to easily produce a default plot with columns just by having the letters on the x-axis and the frequencies - and producing equally spaced columns with the letters in the middle. Or maybe I have overlooked something?

The help page for ColumnGraph wasn't to much help. In contrast to what is usually seen in the help pages, it started out with some very difficult scene, and it was hard for me to deduce anything at all for my easy situation - which again then doesn't seem to be that easy afterall. 


@tomleslie Yes it works that way, but still is using the properties of the normal distribution, i. e. the mean can be put "outside" which makes it possible to accomplish the job by just creating one single sample. Maybe I have confused the situation by connecting my more general question to this specific problem, which can be solved more easily. I think I will close my question here and get back if I later stumble upon a situation where this shortcut is not possible. 


Thanks to both of you, Carl Love and Acer. Very valuable information indeed.


@Daniel Skoog Thanks for the information, Daniel. 

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