On Tue, Aug 30, 2022 at 10:14:21PM -0700, 'Nasser M. Abbasi' via FriCAS -
computer algebra system wrote:
> I am learning Fricas with the hope I can write Fricas script for CAS
> integration tests directly.
>
> I am having hard time figuring how to check the type of variable. I looked
> at Fricas book but it shows no examples.
>
> (11) -> n:Integer
> Type:
> Void
> (12) -> n:=10
> (12) 10
> Type:
> Integer
> (13) -> typeOf(n)
> (13) Integer
>
> Now I want to check, using if then else, that "n" has type "Integer". How
> to this? For example, this gives error
But why do you want to do this? When you declare that variable
is of type Integer, then it has this type, no need to check.
I could say more about 'typeOf', but there is good chance that
what you really want to do is something else. Intstead I give
you an example:
(13) -> 1::Expression(Integer)
(13) 1
Type: Expression(Integer)
(14) -> typeOf(1::Expression(Integer))
(14) Expression(Integer)
Type: Type
(15) -> retract(1::Expression(Integer))@Integer
(15) 1
Type: Integer
Note 1: In simple uses 'typeOf' is redundant becase interpreter already
prints types.
Note 2: Something that logically is an integer may be embedded in
larger type. 'retractIfCan' allows you to check if expression has
integral value. If you are sure that value is integral, then
'retract' is simpler.
--
Waldek Hebisch
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