I want to solve for the roots of a polynomial, such as a x^2+b x + c = 0, for which the output is only the positive root. All coefficients/variables in the polynomial are positive. 

Recently, someone posted an answer to a question where at some point they performed this task and their solution was really slick. But I can't find it. The answer used either solve, or eval or something like that. (Yes, I did perform a search via the MaplePrimes search before asking this question.) 

Here is one that the students generated which caused confusion. 

a := 0.76;
eq1 := 2*cot(a*sqrt(2*E)) = (2*E-5.4)/(sqrt(E*(5.4-E));
solve(eq1, E)

And the results are: 0., 4.411954070, 2.423743792

The problem is with the second answer because it does not exist. If we plot the LHS and the RHS of eq1 vs E where E=0..5.4

And it gets more interesting, if we calculate:

solve(evalf(eq1), E)

The answers are: 0., 2.423743793, 14.33807304+27.39159712*I

where the 3rd answer is again incorrect.

Finally, if a = 0.8 or larger, the incorrect answers disappear. 

Note - fsolve does handle this problem correctly. And despite my attempts to remind them to use fsolve, they see the solve command as the universal truth. Apparently this will be another teaching moment for next year.

So any thoughts about why this happens and why there is a difference in the outcomes between 0.76 and 0.8 for the value of a?

Simple issue. I think it is a bug, but if not, it tends to cause logic problems with new users of Maple.

with(plots):
z := A*x*y:
A:=1.0:
plot3d(z, x=0..1, y=0..1); # works as expected
contourplot(z, x=0..1, y=0..1); # works
fieldplot(z, x=0..1, y=0..1); 
    --> Error, (in plots/fieldplo) invaled 1st argument (the function) 1.0*x*y

Is there something special about what the fieldplot expects for the function? I don't see it in the help. Or is this a bug?  

Yes, there is a work around, define all constants first

A:=1.0:   z := A*x*y: fieldplot(z, x=0..1, y=0..1); 

But I fail to understand why my example should fail. (Note, I have seen this situation for every version, so it is not new.)

What method of worksheet dissemination maximizes the number of recipients and methods of access?

Our students do have access to Maple on campus. However some students beyond our campus do not. Hence I'm trying maximize the number of recipients. This means that the recipient can accesses my worksheet either via tradition computer OSs such as Mac, Linux, Windows, or via tablet / personal computer OSs: iOS or Android. 

For a static worksheet, I've found PDF is the obvious choice. However, I'm writing more modifiable worksheets. The most obvious options I see are:

* MaplePlayer
* MapleCloud
* Maple WWW, by DigiArea Team

In investigating the options, I have found that:
* Maple Player is useful to those who have no access to Maple, but there appears to be no Android/iOS version of it.
* MapleCloud looks very promising since all OSs read the web, but there appears to be no way a person can join a private group via the MapleCloud website. Am I missing or misreading the help?
* Maple WWW, while pretty, appears to be painfully slow on a tablet (at least the examples I looked at).

Thus the initial purpose of this post is to answer the questions I raise, which I view as far more strategic, with more nuances than most questions that appear on this forum. And the second purpose is to initiate more discussion among the users year, particularly from the educational community, about guiding the direction of Maple.

I look forward to your comments and suggestions.

fieldplot is a wonderful tool for plotting vector fields. The option 'fieldstrength' is very useful to scale the arrows so that one can better visualize the field. I often use fieldstrength=log.

However, if one includes the RealDomain library, the fieldstrength=log option fails. I don't see why it should. Can someone enlighten me before I report this as a bug.