The inequal function is not recognized (as part of the plots package) because the with command inside the proc is ineffective - which the startup code editor tells you. If you remove the with line, and call plots:-inequal rather than just inequal, the error will disappear. The with command is really made for interactive usage at the top level only, i.e. outside any procs or modules.

Furthermore, the "value" keyword should be enclosed in double quotes, which you did everywhere except for line 13.

The sum command implements far more advanced methods than simply adding each term. For a start, set

infolevel[sum]:=5:

before calling sum. I won't go into details, though.

Moreover, if you don't like the default behaviour of factorial(-1), you can modify it as follows:

restart:
NumericStatus( division_by_zero );
factorial(-1);
NumericStatus( division_by_zero );
MyHandler := proc(operator,operands,default_value)
   # MyHandler issues a warning, clears the status flag, and then
   # continues with the default value.
   WARNING("division by zero in %1 with argument(s) %2", operator, operands);
   NumericStatus( division_by_zero = false );
   return default_value;
end proc:
NumericEventHandler(division_by_zero=MyHandler);
factorial(-1);
NumericStatus( division_by_zero );

More details can be found under ?NumericEventHandler. Note that we're not modifying the factorial command as such!

It might be easily overlooked, but there is a short paragraph on that topic in the Description section of the ?assume help page:

Assumptions made on names can be removed by unassigning names. For example, having made assumption(s) on x, x := 'x' clears them.

The interface setting that nm is referring to just determines the way assumptions are displayed.

If you don't need the flexibility of ListDirectory, and want to save a few keystrokes, the older listdir command will suffice.

Kitonum is right; the colorscheme option was added in Maple 2016. Please see www.maplesoft.com/products/maple/new_features/maple2016/index.aspx for the details.

Have you seen the book list at www.maplesoft.com/books/search.aspx?category=5?

Currently 65 entries for that category, including non-English books.

There are various way to extract points from a plot and to store them in a spreadsheet. Attached is one that I find simplest: let BodePlot just output data Matrices (where column 1 contains the frequency), combine them into one, and write that to a file, using defaults: BodePlot-export-Excel.mw
(I have chosen a filename that is more specific than File_1.mw, making it easier to find.)

You could also write to other cell ranges, to separate sheets in the same file, or to separate files. Please review the ?ExcelTools,Export help page carefully, notably the examples.

For other plot commands, plottools:-getdata is convenient to extract point coordinates.

Recently (weeks ago) I had the same problem on one of my machines, and it turned out to be a side effect of a certain Physics update that had meanwhile been fixed. So if you are using the Physics package, make sure to keep it updated.

If the problem persists, please tell us the output of Physics:-Version();

You got it almost right; the command is SetProperty rather than setProperty.

Furthermore, I would check "Continuous update on drag" (or "Update continuously while dragging"  in older versions) in the Component Properties dialog for the slider.

If so, then I guess the answer is obvious. ;-)

But if you have specific feature suggestions, feel free to send them to support@maplesoft.com and/or discuss them here.

You didn't provide any executable example (code snippet or worksheet), but this is how it is done in principle. Suppose sol is your procedure returned by dsolve/numeric. Then, after the halt has been triggered:

sol(eventfired=[1]);

For the details, please see section "Interactive features" under ?dsolve,numeric,Events.

About question 2: insert

interface(warnlevel=0):

before calling sol.

But I would not suppress warnings globally. In general, they are useful. I've set warnlevel to 4 in my initialization file. Default value is 3.

Your original get_plot procedure issues no warning because it is technically correct.

If you want to see additional diagnostics, then do

maplemint(get_plot);

Note that maplemint has been updated in Maple 2018; please see Help > What's New > Language & Programming.

newsys := eval([e||($1..10)],mu=5);

Have you tried the TripleScalarProduct command of the Student:-MultivariateCalculus package?

To see the policy, just follow the About link at the top right of MaplePrimes, and see bullet item 1:

... as well as general interest topics in math and computing.

Which doesn't mean that we're all eagerly waiting for homework questions, though. ;-)