Sqrt of constant representation in Julia Symbolics

Question

I am looking for a way to represent a symbolic expression such as sqrt(3)*x so as to avoid sqrt(3) being calculated upfront.

Sample code:

using Symbolics
@variables x
y = sqrt(3)*x

Showing y, we can see that sqrt(3) has become a floating point.

Is there a mechanism to keep the sqrt in symbolic form?

Contingent

Are you speaking of (1/3)x or (1//3)x ? Because (1//3)x works as expected... – Roodepoortmaraisburg

Answer 1

is there a mechanism to keep the sqrt in symbolic form?

julia> using Symbolics
julia> @variables x
(x,)
julia> y = Symbolics.Term(sqrt,[3])*x

x*sqrt(3)

Palmer

Thanks for your nice answer. I have been looking for Symbolics thorough documentation but only found something basic. Could you provide a pointer. – Contingent

Answer 2

I cannot reproduce:

julia> using Symbolics

julia> @variables x
(x,)

julia> y = 1//3*x
(1//3)*x

julia> y
(1//3)*x

My config:

[0c5d862f] Symbolics v0.1.21

and

julia> versioninfo()

Julia Version 1.6.0
Commit f9720dc2eb (2021-03-24 12:55 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i7-9850H CPU @ 2.60GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, skylake)

Roodepoortmaraisburg

Sorry, I remember the problem. It was sqrt(3). Thanks for your follow up though. I have updated my question. – Contingent

Answer 3

Funny, y = 1//3 * x works, but not y = sqrt(3) * x as according to the orignal question. So, the answer from user Nasser is really helpful thanks.

Highbinder

Thinking about it, when calling sqrt with am integer of float, multiple dispatch will call sqrt(::Int64) or sqrt(::Float64). However, when using the // operator between an Int64 and a Symbolics Num, multiple dispatch will select the corresponding function with a signature operator // (Int64, Symbolics.Num) – Contingent