@Kitonum 

Thank you, @Kitonum! Please be kind anough to read my response to @MapleMathMatt above.
I will also keep your wonderful solution for the future.

With besr regards,

mapleatha

@MapleMathMatt 

Thank you very much! I appreciate it. I already did the following:

The pice of Maple code I gave you is part of an animation display, say, ANIM.
I exported ANIM as a GIF file and then loaded the file to Photoshop 2020.
Photoshop now contains all 50 frames of ANIM.
(1) I opened a new transparent layer and pasted the word "sin(x)" in red, and a better
convenient size, at the appropriate position onto this top layer.
(2) I selected only this layer and the bottom No. 1 layer
and then saved the file as a GIF image.
I am done with ANIM!
I did this after I inquired at the Photoshop forum about the possibility of quickly pasting something
to all the 50 layers of a GIF image. As you can see, you don't have to paste the red "sin(x)"
image over the black one to all the layers. Just one only.
This method takes only a couple of minutes and may be appled to any number of changes
we need to make to the title of an image.
I will keep your suggestion in mind for the future.
Thank you so much again.

mapleatha

@dharr 

Thank you, dharr.
I appreciate it.

mapleatha

@tomleslie 

Thank you, tomleslies. Your suggestion by email worked fine.

mapleatha

@tomleslie 

None of them works. I get just a plane in one of them, the 3d one, and just the axes in the other one.

I do add with(plots): and with(plottools):

Thank you, tomleslie!

mapleatha

@Kitonum 

Thank you, Kitonum. I know "diff", of course. I just wanted to use the linear differential operator D.

mapleatha

@Carl Love 

This is just great, Carl!
I also applied "unapply" to other definitons independent of the underlying varaible x.

Thank you!

mapleatha

@acer 

Once again, @acer, Thank you very much. I really appreciate it.

mapleatha

@Kitonum 

Thank you, Kitonum.
I appreciate it.

mapleatha

@Kitonum 

Thank you very much, Kitonum.
mapleatha

@acer 

I can't believe you, acer? Can't you see that it does whatever it pleases with the order of the factors in the denominators?
Who knows what it will do with fractions and sums of fractions with 10 factors. Hahahaha!
We need the order of terms in the sums because we want to manipulate those terms much further. That is how you also teach partial fractions. You don't give the students any order Maple gives you as an answer. By replacing things with RTABLES many thngs get straightened out. Not only sums from partial fraction decomposition. I gave you a triival idea as to how you use RTABLES. This is the end of this entire discussion.
 

@acer 

Here is a reply to my message of 2017 by "vv 8008"

In Maple it is difficult to control the order of the terms in a sum (the sort command is mainly for polynomials).  
Maple does this for efficiency reasons; after all it was designed for computations rather than typesetting (where LaTeX is anyway the preferred tool by mathematicians).

In recent versions it offers however many typesetting options (see ?Typesetting).

@acer 

HERE:

@acer 

Are you actually saying, after all those years of experience, that Maple does not change the order of things?
You must be kidding. I have written programs in Maple that will give me 1000 partial fraction decompositions
in a few seconts with all kinds of messed up orders that you can imagine. My specialty is differential equations and this is where most of my reasearch is. Are you going to apologize to me when I give you acceess to all those messed up orders?
mapleatha

@acer 

Here is one more:

print(RTABLE(1,Matrix(2,2,[[1-lambda,1],[1,-lambda]]))*RTABLE(1,Matrix(2,1,[u[1],u[2]]))
=RTABLE(1,Matrix(2,2,[[-1,1],[2,-2]]))*RTABLE(1,Matrix(2,1,[u[1],u[2]]))*` = `*RTABLE(1,Matrix(2,1,
[[0],[0]])));

Result:

Any more complaints?

Thank you guys.

mapleatha