I/O, Saving, and Latex

Note that Julia's standard I/O functionality can be used to save Symbolics expressions out to files. For example, here we will generate an in-place version of f and save the anonymous function to a .jl file:

using Symbolics
@variables u[1:3]
function f(u)
  [u[1]-u[3],u[1]^2-u[2],u[3]+u[2]]
end
ex1, ex2 = build_function(f(u),u)
write("function.jl", string(ex2))

Now we can do something like:

g = include("function.jl")

#2 (generic function with 1 method)

and that will load the function back in. Note that this can be done to save the transformation results of Symbolics.jl so that they can be stored and used in a precompiled Julia package.

Latexification

Symbolics.jl's expressions support Latexify.jl, and thus

using Latexify
latexify(ex)

will produce LaTeX output from Symbolics models and expressions. This works on basics like Term all the way to higher primitives like ODESystem and ReactionSystem.

Per-variable LaTeX names

Attach a latexwrapper to a variable to choose its LaTeX rendering independently of its Julia name (similar to SymPy's Symbol(r'\omega_{0}')):

using Symbolics, Latexify

@variables x t
@variables w0 [latexwrapper = s -> raw"\omega_{0}"]
@variables vx(x, t) [latexwrapper = s -> "v_{x}"]

latexify(vx + w0^2)
# v_{x}\left( x, t \right) + \omega_{0}^{2}

The wrapper is a function from the symbol's string name to a LaTeX fragment. That fragment is emitted verbatim, so underscores and carets are not escaped. Without latexwrapper, multi-character names are wrapped in \mathtt{...} by default.