@J Rod 

I have a large file which was started with Maple 2015, updated with Maple 2016, then updated again today with Maple 2016.1.  When I open it this evening with Maple 2015, many statements that involved a mouse click are now messed up.

I even have two graphs which are still displayed, but the statements that generated them are completly missing.

To fix it, I tried to copy a similar plot statement, paste it in, and adjust it appropriately for the missing plot statement.  You can guess what happened next - the same error as started this thread:

Error, incorrect syntax in parse: `;` unexpected (near 4th character of parsed string)

Yes, I can retype it wth Maple 2015 and recreate the graph, but that is crazy.  Not only does Maplesoft owe users an apology, a correct version 2016.2 promptly, but also a new program that can read a file trashed by 2016.1 and correct the errors inserted by 2016.1.

Thank you both for the prompt, helpful replies.

Thanks for the details of a home-grown procedure.  That more or less works for me, until a student ask why are you using that my... procedure, when Maple has one without the "my" prefix.

Actually, now I have to tell students that Maple ruined a great procedure with Version 17, and each student has to copy and use this alternative procedure to get the equation of a tangent line.  Alternatively, they can carry out the steps on their own.  That is, evaluate the curve at the specified point.  Compute the derivative of the curve and evaluate it at the specified point.  Then add those two results while including a parameter multiplying the tangent vector.

The last two replies illustrate the sequence of commands.  That example is not too bad.  Try it again with this vector function (space curve)

sin(t)-t*cos(t), cos(t)+t*sin(t), t^2

Think about this in the context of teaching Vector Calculus and using Maple as a tool to help student comprehension.  This is an absurd change, in my opinion.

@PatrickT 

it is not fixed.  I just tried to reply to another post.  The only difference is that I did not receive the message about "something went wrong."  The reply just did not post.  Using MS IE 9.

@Markiyan Hirnyk 

Well, let's see if the reply bug has really, really been patched....

I dislike the cX or CX or XC notation, because I've never seen it in any textbook.  I need to be consistent with the textbook in use in any course.  Therefore, I need both

X^c  and X'

to work to compute the complement, or at least to denote the complement, without the convert to atom every time the symbol is used.

I see your C() works to show a typical set identity, but without a way to define the intended universal set in any particular situation, all it does is replace X with the elements list in X. 

X:={1,2,3}

CX=C{1,2,3}

Duh! That's no help at all.

@Markiyan Hirnyk 

Well, let's see if the reply bug has really, really been patched....

I dislike the cX or CX or XC notation, because I've never seen it in any textbook.  I need to be consistent with the textbook in use in any course.  Therefore, I need both

X^c  and X'

to work to compute the complement, or at least to denote the complement, without the convert to atom every time the symbol is used.

I see your C() works to show a typical set identity, but without a way to define the intended universal set in any particular situation, all it does is replace X with the elements list in X. 

X:={1,2,3}

CX=C{1,2,3}

Duh! That's no help at all.

@Markiyan Hirnyk 

Thanks for your efforts.  I thought I had tried that with Maple version 16 in the fall.  Maybe not.  I did not try it with Maple 17 today.

But even so, that is still an awful way to have to go.  It looks fine, but every time you want to refer to the complement of X you have to again make it atomic.  What a pain.

Maple needs an enhancement to make it reasonable to refer repeatedly to the complement of a set.

@Markiyan Hirnyk 

Thanks for your efforts.  I thought I had tried that with Maple version 16 in the fall.  Maybe not.  I did not try it with Maple 17 today.

But even so, that is still an awful way to have to go.  It looks fine, but every time you want to refer to the complement of X you have to again make it atomic.  What a pain.

Maple needs an enhancement to make it reasonable to refer repeatedly to the complement of a set.

VERY FRUSTRATING!!!!!!!!!!!!!!!!