Symbolic sqrt(2) and sin(pi)

Specific Domains
5

Okay so:

julia> using Symbolics
[ Info: Precompiling Symbolics [0c5d862f-8b57-4792-8d23-62f2024744c7]

julia> Term(sqrt, [2])
ERROR: UndefVarError: Term not defined
Stacktrace:
 [1] top-level scope at REPL[1]:1

julia> Symbolics.Term(sqrt,[2])
sqrt(2)

Am I supposed to spell the using differently to make Term accessible (apart from just using Symbolics: Term)?

It seems that Term works more or less as I would expect for element:

julia> expr = Term(sqrt,[2])
sqrt(2)

julia> expr * expr
sqrt(2)^2

julia> expr * expr + 1
1 + sqrt(2)^2

julia> @syms x
(x,)

julia> expr2 = x + expr
x + sqrt(2)

However if I now substitute an exact value for x I get a floating-point result:

julia> substitute(expr2, Dict([x => 0]))
1.4142135623730951

How can I:

  1. Explicitly request for an expression like sqrt(2) to evaluate to an approximate floating point result with some specified precision/digits
  2. Prevent the numerical evaluation when performing an exact substitution.
  3. Evaluate something like sin(pi) exactly.

(Feel free to point to any docs that explain this but I’ve skimmed them and I don’t see these things explained or any mention of Term.)

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