I was wondering how Maple cope with piecewise functions during forward integration and if it's preferable to use dsolve events option in place of defining a piecewise discontinuos function.

As far as I understood dsolve/events halts the integration each time an event is triggered and subsequently restarts the integration using the pre-trigger outputs as new initial conditions. I suppose that by using a piecewise, if a discontinuity is detected, dsolve proceeds exactly in the same way halting and restarting the integration.

Here a toy example of a 2D rolling dice (idea of a rolling dice from the rolling cube by @one man :P ) in which the reaction forces of the floor can be seen as function of the compenetration dice/ground

Both the appraches (events and piecewise) give the same results

falling_dice.mw

Maple 2018 memory usage increases as I try to display or manipulate the expression presented in  test_maple2018.mw. The same worksheet works perfectly in Maple 18

I've tried both in Maple 2018.1 and Command Line Maple 2018 obtaining the same result

Maple 2018.1, X86 64 WINDOWS, Jun 8 2018, Build ID 1321769

From command line maple 2018 when trying to evaluate

memory used=3.6MB, alloc=40.3MB, time=0.14
memory used=4.7MB, alloc=72.3MB, time=0.19
memory used=33.3MB, alloc=107.3MB, time=0.45
memory used=109.2MB, alloc=143.1MB, time=1.37
memory used=217.7MB, alloc=185.6MB, time=2.60
memory used=292.6MB, alloc=217.6MB, time=3.87
memory used=328.0MB, alloc=254.6MB, time=5.16
memory used=437.3MB, alloc=299.9MB, time=7.44
memory used=549.8MB, alloc=335.9MB, time=13.60
memory used=630.9MB, alloc=375.4MB, time=17.07
memory used=686.9MB, alloc=401.8MB, time=19.61
memory used=785.6MB, alloc=431.9MB, time=22.31
memory used=944.8MB, alloc=427.9MB, time=26.74
memory used=1150.1MB, alloc=427.9MB, time=32.37
Interrupted

I was wondering if my Maple 2018.1 installation is corrupted. Since I have no acces to other Maple licenses, can anyone try to execute it? test_maple2018.mw

Hi all, is there a reliable way to hide/obfuscate the source code of a maple library file (*.mla) (e.g. if you want to redistribute it)?

From what I know, since it has to be into the archive, any not exported (or hidden) procedure can be easily viewed setting kernelopts(opaquemodules=false) or through LibraryTools:-Browse.

Hi All,

I recently switched from Maple 18 to Maple 2018. I was trying to execute and old worksheet created with Maple 18 in which a DAE have to be solved numerically. In Maple 18 the worksheet works flawlessly whereas Maple 2018 throws 'Error, (in dsolve/numeric/process_input) invalid specification of initial conditions...'

Initial conditions are given in the form {x1(0) = 1, x2(0) = 2, D(x1)(0) = 1, D(x2)(0) = 0 ....} and are the same in both cases ( I merely executed without any modification the same worksheet in the two Maple versions).

I feel I've missed out something in the changelog... any idea on what is happening?

PS. call to dsolve

dsolve(dsys_numeric, numeric, implicit = true, stiff = true, optimize = true, compile = true):
 

As I work a lot with lists (need to merge them frequently), I would like to redefine the `union` operator in such a way that it will merge two lists together. It would makes thing more efficient than writing 

list1 := [a,b,c];
list2 := [d,e,f];

newlist = [op(list1), op(list2)];

I've already tried

`&union` := proc(list1, list2)
  [op(list1), op(list2)];
end proc:

[a,b,c] &union [d,e,f]

but it's not what I'm looking for. In fact I could have used any name after the `&`... and really don't like having to type the & at the beginning (is there a way to define an infix operator without having to use the `&`?)

Maybe creating a module to override  the original definition?

my_module := module()
  export `union`:

  `union` := proc(foo,bar)
      if some_trigger then
         # return something
      else
         # use global `union` definition
      end if
   end proc:

end module;

Any suggestion?

P.S.

- I generally don't use the original set union operator, so redefining it is not an issue;

- I have to use lists