Reading another question today I discovered that I can use syntax like

a := 2 _i + 3 _j

b:= _i - _j

a+b  

Maple computes the sum by vector component. This is very useful, and it prompted me to start reading the Multivariate Calculus Study Guide. I am still going through it but haven't seen this particular notation yet. When I check the type of a above I get a result that sort of looks like `+` but actually it seems to be tilted to the right (so I guess it is italicized and represents some symbol).

What is this type?

I don't find much searching online, and I did see this page that says 

"Any symbol beginning with an underscore (_) is effectively reserved for use only by library code. It is not available to users. Failure to observe this rule can lead to unexpected results."

Edit: After a bit more looking, looks like my example code is using notation available from the Physics package, which I am now reading a bit about (but it is not clear to my why this package is used since I am not importing it explicitly).

I noticed something that seems to be new to my usage of Maple.

As I am typing in an expression in a Maple Worksheet (Document Mode), it seems Maple goes into "Evaluating" for a split second on every new keystroke.

For context, I have my own worksheet open and also the Maple Study Guide open for Multivariate Calculus. But just now I closed it and restarted Maple. A brand new worksheet has this same behavior. 

Did I just miss this before or is it normal for Maple to show "Evaluating" for a split second on every keystroke (instead of just "Ready")?

I just wrote up a bug report (aka "Software Change Request") but got a "We are currently experiencing technical difficulties" error so the report is not being sent.

I will just post here about the bug in case anyone knows what it is.

I am going through the Multivariate Calculus Study Guide. I went to section 1.1, and was going through the examples. At the end of an example is a link "Next Example", but when I click this I get an error and have to go back to section 1.1 Table of Contents. Kind of annoying. Also, I notice that Maple simply crashes seemingly randomly when going through this study guide. Very annoying.

Here is a screenshot of the write-up to the bug report service that isn't working, for the record

I was wondering if this is something wrong with my Maple installation or if other people experience it too.

I was just trying to follow along the Multivariate Calculus Study Guide.

There is an example where we are supposed to plot a "rooted vector". Basically, a vector where the tail is not at the origin.

The commands seemed pretty straightforward but are not generating the expected results. Here is a worksheet with the commands in question

Well wouldn't ya know? I am finally able to execute a worksheet in this question box. As you can see there is no vector being displayed. Now, after playing around with the values a bit, it seems that the root that I chose, [-2,1], seems to be the only one that won't work. In particular, the value 1 there seems to be problematic. If I use any other value (including for example 0.9999999), the vector seems to be drawn correctly. 

Why doesn't it work for the original parameters I chose?

Download PlotRootedVector.mw

Is there a command to generate a second-difference matrix of size n by n?

This matrix has 2s on its main diagonal and -1 above and below each main diagonal element.