@Carl Love 

Thank you for pointing out that eval(g(x),x=2) is not good.

But, I can't understand why it is bad. So, I am glad if you add some explanation about this.

For, it looks to me the same as

f:=x->x^2;

f(x);#which is x^2

g:=x->diff(f(x),x)# which is x->diff(x^2,x)

g(x);#which brings diff(x^2,x), that is 2*x

eval(g(x),2);#which means 2*2

taro

@alfarunner 

If you don't like using if with quotes, then you can change the definition of f as

f:= (x,a)->piecewise(x<a,0,(x-a)^2);

as is easily written through referring to  the link I showed above.

@Maple4evergr8 

I read in a book that a lot of modifications with formulas of mathematics are done using combine, which

differentiates it from expand or simplify.

 @Carl Love

@Thomas Richard 

 sort([[9], [4], [7], [2], [5], [8], [3], [6], [1]], key = (x->x[1]));
         [[1], [2], [3], [4], [5], [6], [7], [8], [9]]

sort( [ [1,1], [2,1], [3,1], [1,2], [2,2], [3,2], [1,3], [2,3], [3,3] ], key=(x->x[1]) );

[[1, 1], [1, 2], [1, 3], [2, 1], [2, 2], [2, 3], [3, 1], [3, 2],   [3, 3]]

Thank you. I could understand the use of key in sort. The above two examples in the help page

was helpful to me to understand  sort,key.

taro

@Carl Love 

Thank you for your kindly explaining your code to me.

%[], `[]`~(%), ~, sort/key were new to me.

I could understand your code owing to you.

Thank you.

Best wishes.

taro

@Carl Love 

Thank you for your code. It is a little difficult to me. So, i will study your code.

Thank you for the material for my study of Maple.

Surely, only five take the form I want the expression to be in.

Probably, I might ask some questions about your code.

Please take care of me, then.

taro

@Preben Alsholm 

Your way is intuitive and very simple one.

I hadn't hit on the way as you wrote.

Thank you.

taro

@Adam Ledger 

When I read the title of oh ok that should be good for me,

I thought that you don't like the present user interface which works on Java.

If my understanding is wrong, I will correct what I wrote above.

Best wishes.

taro

@Kitonum

Thank you. Surely, your way is a way.

As it is, however, not so much different from the way I wrote,

I think that what you taught in your reply is that there is no easier and more intuitive way to the problem 

I wrote, though that modificaion looks apparent. Is this right?

taro

@ 

I don't have so heavy file. So, in opening my files, I need only a few seconds.

This might be the reason I felt that the present user interface does not have so much inconvenience.

taro

@

@Adam Ledger 

I can't understand why you hate Java so much.

At the time of Maple9.5 being sold, it needed a high spec of pc, so with my white mac, I found I couldn't

use it. But, since a version of probably 18, the speed of Maple astonishingly became fast.

So, I don't have any inconvenience to use the present standard user interface.

If bugs are taken away, any standard user interfaces would be good to me.

taro

@tomleslie 

Thank you. I checked what you write with your worksheet.

Best wishes.

taro

@John Fredsted

Thank you very much for checking what I wrote and for creating your file and finding the behavior I described.

And, thank you for your clearly explaining that phenomenon.

I experienced the same thing as you had. For a simple file, I found that behavior of maple, but, when I opened the

same file later, command + f worked well, though it is strange.

So, I created the more complex file which I posted  here,  from the original file.

Double _ is nice to use, as the subscript characters are shown like so.

But, there might not be other ways to avoid that defect of maple other than the way you write, that is to use a single _.

Thank you.

Best wishes.

taro

@John Fredsted

@Carl Love 

Thank you for telling me about my PS.

taro

@Kitonum 

Thank you for your simple codes to gain the output which can be derived

from Mr. Christian Wolinski's code.

Best wishes.

taro