Dear Maple users

I am defining various geometrical items in the plottools package and finally plot them using the display command. Let's say I have defined:

Circle1:=circle(...):

Circle2:=circle(...):

Line1:=line(...):

etc.

and finally want to plot them with the display command:

display(Circle1,Circle2,Line1,...)

It works, however sometimes I only want some of these items to be plotted. Certain variables at the beginning of the document do control if those items should be plotted or not. Let's say a variable CircleOrNot can be set to have the values "no" or "yes", and if I set it to "yes", it should plot it and if the value is "no", it should not plot it. I know that I can make a conditional statement in the end when dealing with the display command, but it can be quite a mess (condition after condition ...).

What I would like is making a conditional assignment like the following:

If CircleOrNot="yes" then Circle1:=circle(...) else Circle1:=null end if

or something like that, and afterwards use the full display command including all objects:

display(Circle1,Circle2,Line1,...)

But it does not work. I receive an error. There doesn't seem to be an empty statement, which will just be ignored by the display command. How can I do it? Probably someone has a good way to handle this situation.

Best regards,

Erik

Dear Maple users

I have a question which may seem very simple, but for some reason I have not been able to find a solution to it in Maple:

If plotting a function in Maple by specifying an x-range, but not a y-range, Maple will somehow find a reasonable y-range itself. That's basic stuff. But how do I ensure that this y-range contains the value 0, and Maple still decide the min and max by itself? I could set it myself, but my worksheet require that it is done automatically independent of the given function at hand. 

Erik

Dear Maple users

As a followup on my recent question about how to count the number of characters in a string containing special Danish characters here: https://www.mapleprimes.com/questions/236478-How-To-Count-Length-Of-String-When-Special

I also need to handle substrings from a string in my work in Cryptography. In my attached file I present an example with a string containing two special characters. The problem is however, that I need to access individual characters in the string. Normally I would do so by using the command substring. As indicated in the file it doesn't work very well, because the special characters are represented by TWO elements (bytes)!

Is there a smart way to create a new command named SUBSTRING to accompanying the great LEN command suggested by vv?

Regards,

Erik V.

substrings.mw

Dear Maple users

I wanted to count the number of characters in a string containing special Danish letters beyond a...z. When using the special Danish letters æ, ø and å, those letters or characters are being counted as 2 characters each. I hope someone can help me having Maple count the length of strings containing those characters properly. 

Regards,

Erik V.

Dear Maple users

I have encountered a very strange error at one of my students. When using functions from the Expression Palette, she receives an error. It happens every time she is using this Palette. A reinstallation of Maple didn't help solve this issue. When using Command Completion for the very same function (for example cosine or square root), it works properly. 

She did send a Maple file to me in order for me to investigate it. I opened it and reexecuted the entire document. The error messages remained. I tried applying the functions from the Expression Palette myself resulting in the same errors. I even opened a new document and tried it again. Still an error. Then I closed Maple completely and opened it again. Within a new document, I applied a function from the Expression Palette. Now it worked!! I can't seem to understand  the logic behind this behavior. The file sent to me by the student obviously contain some kind of error, but why will this error spread to a new document, which I have opned on my own computer? My own computer does not have any issues with Maple. 

I have attached the Maple file with the errors and a screen shot. I hope someone can explain this strange behavior and tell me how I can help this student make Maple work again. 

Kind regards,

Erik V.

Maple file:

Error.mw