On 12/23/23 21:53, 'Nasser M. Abbasi' via FriCAS - computer algebra
system wrote:
What I meant to say, the lists in Fricas have to be same type, else it will
not work with concat. Here is an example
20) -> L1:=[1,2,3]
(23) -> L2:=["D","E","F"]
(24) -> concat(L1,L2)
gives error.
Yes. And it should give an error. Elements of a list must be of the same
type.
However...
You can create a Union type.
%%% (1) -> l1:=[1,2,3]
(1) [1, 2, 3]
Type: List(PositiveInteger)
%%% (2) -> l2:=["D","E","F"]
(2) ["D", "E", "F"]
Type: List(String)
%%% (3) -> U ==> Union(Integer, String)
Type: Void
%%% (4) -> LU ==> List U
Type: Void
%%% (5) -> l1::LU
(5) [1, 2, 3]
Type: List(Union(Integer,String))
%%% (6) -> l2::LU
(6) ["D", "E", "F"]
Type: List(Union(Integer,String))
%%% (7) -> concat(l1::LU, l2::LU)
(7) [1, 2, 3, "D", "E", "F"]
Type: List(Union(Integer,String))
FriCAS also has a type "Any". So you could do
%%% (8) -> concat(l1::List(Any), l2::List(Any))
(8) [1, 2, 3, "D", "E", "F"]
Type: List(Any)
'Any', however, is a weird thing. It can somehow be considered as the
all-type, but on the other hand, an element of it is actually a pair,
consisting of the value and the type for that value. So it is NOT the
same as forgetting about types.
Anyway, I am not sure that you really want to use Any in your program.
But in Maple using op()
L1:=[1,2,3];
L2:=["E","F","G"];
L3:=[ op(L1) , op(L2) ];
L3 := [1, 2, 3, "E", "F", "G"]
op() also work on any expression,
op(sin(x)+cos(x)+exp(y))
gives
sin(x), cos(x), exp(y)
Does Fricas have op()? whe I did ?op it said no. How does one then extract
all the operands of expression in Fricas?
The sad answer is "no". FriCAS does not have op() that is like in Maple,
but that is due to the fact that FriCAS works fundamentally differently.
First, you should know, what the type your "expression" actually is.
Say
)type on
and the type of your expression will be shown (similar to above).
If it is 'Expression(Integer)' then look at
https://fricas.github.io/api/Expression.html
and check which function could apply. In particular for
Expression(Integer) you should understand that it actually is a rational
function an many "variables". These variables are called "kernels"
(FriCAS type 'Kernel').
You can list all the kernels of your expression by calling
kernels(expr)
Let us take
%%% (1) -> expr := sin(x)^2 + tan(x)*x^3
3 2
(1) x tan(x) + sin(x)
Type: Expression(Integer)
%%% (2) -> kernels expr
(2) [tan(x), sin(x), x]
Type: List(Kernel(Expression(Integer)))
%%% (3) -> isPlus expr
3 2
(3) [x tan(x), sin(x) ]
Type: Union(List(Expression(Integer)),...)
I hope, from here you can get a bit further.
Ralf
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