@acer  I have a sense of what is going on here and now know how to advise the students in the future. Frankly, I would prefer both groups to be of the same type, either a mutable structor or not, rather than different types since it is easier to educate others without explaining this difference. 

@Tegewaldt 

1) Since you are getting started, allow me to recommend "Worksheet" over "Document" mode. In teaching Maple to students and colleague at a college for many years, "Document" mode is fabulous if you are skilled in Maple code. Otherwise, it is more of a hassle in spacing, execution, etc. Worksheet is what you want. To make sure you always use worksheet, in Windows, select tools -> options -> the interface tab -> and then change default format to Worksheet. (On a Mac, under Maple 2019, select preferences -> interface tab -> change default format.)

2.) You don't have to use the notation g := x-> function.   You can write g(x) = function.  And yet, if you look at the Maple output, the format tells you what you are actually doing. g is a entitity which takes the value in x and puts it into the function. Here it is not needly complicated. That said.

3.) I do agree with you that "g" "colon" "equal" "x" "dash" "is greater than" your function is NOT intuitive and has been a reason some of my colleagues simply won't adopt the program since they simply don't use it enough to remember to code it this way. Hats off to Maplesoft for allowing us to use the mathematics the way we learned it in early school. Maple should be solving math, not about learning a new coding system.  Here the only new coding you have to learn is the difference between "assign" and "equivalent". Personally, I find this more intuitive that how Python /C++ does it where "=" means assign, and "==" means equivalent. Shouldn't "=" mean "equals"?

4.) In having Maple answer one's math problem, the "D" operator (or is it a function? Or both?) makes no sense to me or others who have seen it. If it differentiates, then with respect to what? I don't use, I don't teach it.

5.) However, what Maple wrote out when I said g(x1) := f '(x1) is not complicated - it is precise. In your mind you are differentiating with respect to x, but then using a different x to evaluate the outcome. 

And the evaluation symbol of a vertical bar with x = x1 is about as standards as I have every seen regardless of where you learned mathematicsl in the globe. Think of how you write to say you are going to evaluate the endpoints of an integral.

If I were the instructor, this would be a good moment to have students think about what is the sequence for solving such a problem. Hence I would walk through this question so that the most readable and accurate outcome is:

g(x, y):=eval(  diff( f(x1), x1) , x= x1)*y

differentiate with respect to a variable, then evaluate with the value stored in another variable.

This long post concludes with encouragement. I agree that there is a level of added complexity to using Maple when people are not 100% familiar with the math they are trying to work with. But on the other hand, it does an abosolutely amazing job considering other mathematical systems out there. 

Download Example.mw

@Doug Meade The poster asks a reasonable question that I would assign as part of a homework assignment for a coding class testing the students ability to append to a data file. However, in this situation, I sense the person asking is of limited ability and so I was tyring to determine a solution which requires the least amount of new function or logic memorization. 

If you run the worksheet and the outcome is some result, you can add a line at the bottom of the worksheet assign to a variable that outcome. Otherwise, you are going to have to be more specific. 

There is a "hacked" version of it out there. Your results are consistant with what others are reporting. 

@acer  Many thanks for quickly replying with a right-on-target solution which I would have never been able to produce myself.  

And to those who develop Maple, please include the size option in the setoptions3d. It is highly desired. Acer's soution is great, but I would prefer to not to use it. I don't want to spend time explaining to the students how to generate a  Maple initialization file, because it increases the chances something will go wrong for them.

I have one huge request. Please fix and enhance the print-preview window.

1. At a minimum, the window should preview with the entire page. I should not have to scroll down to see what the last line on the page is.
2. Better yet, allow the user to set a zoom percentage that is remembered so that when the user print-previews a document, it uses the same zoom percentage. This setting should be the same for all documents.
3. As an enhancement, add a “go to page” button so that one does not have to click through 13 pages to see what page 14 looks like.

Thank you.

Baldy area????????

... and make them 2d pineapple and peppers! 

@nm For me, I appreciate the option to choose "what you see is what you get" or the classic mode. I equate the option of different styles to being more inclusive. Pedagogically, the 2D math mode helps getting folks started with Maple more quickly. But when I need more complex and long code, I switch to 1D typesetting.  However, this problem shouldn't occur regardless of the format.

@nm It appears to be a math mode issue:

@Carl Love The system is equivalent to long wires with constant current interacting with each other, but this person's example involves gravity. I've never read about such an example discovered in nature. But if you can link me to an example of long thin masses for which the dominate force is gravity, I'm happy to add that to my collection. 

If the idea is to mimic a magnetostatic force of the wires, then I suspect this is a unrealistic since the moving of the wires would affect the current in the wires. Upon reflection, this leads to a very cool computational (and realistic) question related to the retarding fields that I could add to a dynamics of electromagnetism course. Thanks!

@Carl Love Yep, that is correct. As for this problem, for the life of me I can't think of a physical justification for modeling gravity as a one over distance interaction.  I'm guessing this is simply a excercise in how to use dsolve with a more readable equation for the force.  When I ask the students to model it, I have them use the physically more accurate expression. 

@taro A good catch. However, in studing concepts in physics, extremum points come up frequently. From a physical perspective, these are two dimensional points: both the location and value of the function at the location are required. Neither of these Student[Calculus1] functions perform this task. Hence I return to the elegance of your original solution. ;-) Have a good day. 

@taro ..especially when your answer is so elegant and understandable. I wonder how often the Student[Calculus1] is used.