I do not use input 2D math in document mode. But was trying it now to see if I can enter this to check my hand solution

In worksheet, this is what I do

restart;
VC:=VectorCalculus:
f:=y*sin(x)+y^2;
VC:-DotProduct(VC:-Del,VC:-Gradient(f,[x,y]))

But I do not know how to enter   if possible, in document mode 2D math. THis is what I tried. Created document mode. Picked the DEL operator from the left side common symbols window. But I do not know how to do the rest.

Clearly I am doing something silly. This is why I prefer plain Maple code, becuase I can see what I am typing :)

But was wondering, how to do the above in docuemnt mode + 2D math? To make it look close to how it shows in the book. Does one need special palette for this?

I wanted to overwrite an existing variable of type table by the one returned from a call to a proc().

But it does not work, unless eval() is called on the returned result from the proc()

But if the variable that recieves the return value from the proc() was not already a table type, then it works without using eval. Why is that? 

Here is an example

restart;
foo:=proc(A::table)
  A["c"]:=3; #add new field
  return A;
end proc;

A:=table():
A["a"]:=1:
A["b"]:=2:
B:=foo(A):
whattype(B);
print(B)

           table(["a" = 1, "c" = 3, "b" = 2])

In the above, it worked. B is table now, and assigned the updated table from the proc.  But 

A:=table():
A["a"]:=1:
A["b"]:=2:
A:=foo(A): #without eval, it does not work.
whattype(A);
print(A)

             symbol
               A

I expected A to be overwritten, just like B was. To fix this, I have to change A:=foo(A): by A:=eval(foo(A)):

But why eval was not needed in the first example, and was needed for the second example?

btw, the same thing happens with Record(), not just table()

just like to understand the reasoning behind this. I expected both cases to work the same way. But it works different if the variable happend to be unassigned (like B above).

Why does Maple product history page   stop at Maple 6, year 2000?

Maple starterd in 1984. There are more versions before version 6. I think this official Maple page should list every release made in Maple and do not understand why it stop at version 6 only.

Wikipedia has more complete and detailed history of Maple products, starting with version 1 in 1982, with minor versions also shown than Maple own official web page gives.

btw, Wilipedia says version 6 was released in December 6, 1999. But Maple official page says version 6 was released in 2000.  

Any help why this code fail

restart;
PDE := diff(u(x,y), y$2 ) + diff(u(x,y), x$2) = 0;
BC:= u(x,0)=0, u(x,100)=100, u(0,y)=0, u(10,y)=0;
sol:=pdsolve([PDE,BC],numeric);

gives

Error, (in pdsolve/numeric/process_PDEs) PDEs can only contain dependent variables with direct dependence on the independent variables of the problem, got {u(0, y), u(10, y), u(x, 0), u(x, 100)}
 

But sol:=pdsolve([PDE,BC])  works OK and gives analytical solution.

What error Am I doing in the above code in this case?

Maple 2020 with Physics 642

Since Maple comes with source code that one can display. Even though it is stripped of all comments, which makes it hard to follow sometimes, I was wondering if there are any tools to help one get the large picture of what is there without having to step and go through all the thousands and thousands of the help pages jumping from one to another and losing the path.

I am looking for something similar to the tree program one finds on Unix, but applied to Maple's logical package hierarchy.

Since Maple has thousands of packages and subpackages and some has sub subpackages and then thousands of commands below all these, such an automated tool will be useful.

For example, I could ask it to show me top level packages and subpackages only (and not show the names of all the functions below that). This will help one see what is out there at a glance. i.e. see the big picture.

Here is an example of tree command I found on the net. But instead of looking at directories, the maple one will look at logical package tree.

For example, I just made short example for the Student package now

But doing the above by hand for everything is not practical. The above is just partial view of one package, and there are hundreds others. 

It will be nice if there is a tool, where one can tell to show the Maple package tree and the level of details to show. This will help one learn Maple better also.

The output of such tool does not even have to graphical. It could plain text, something like this

Student
      LinearAlgebra
               Basis
               IntersectionBasis
               etc.....
      Calculus1
               ......
               ......
Physics
DataSets
.....

      
       

Alignment is done using tabs for example to help show the structure.

Any suggestions?