Operators

Pre-defined

All Base julia operators that take 1 or 2 float32 as input, and output a float32 as output, are available. A selection of these and other valid operators are stated below.

Binary

plus, sub, mult, pow, div, greater, mod, beta, logical_or, logical_and

Unary

neg, square, cube, exp, abs, logm (=log(abs(x) + 1e-8)), logm10 (=log10(abs(x) + 1e-8)), logm2 (=log2(abs(x) + 1e-8)), sqrtm (=sqrt(abs(x))) log1p, sin, cos, tan, sinh, cosh, tanh, asin, acos, atan, asinh, acosh, atanh, erf, erfc, gamma, relu, round, floor, ceil, round, sign.

Custom

Instead of passing a predefined operator as a string, you can define with by passing it to the pysr function, with, e.g.,

    pysr(
        ...,
        unary_operators=["myfunction(x) = x^2"],
        binary_operators=["myotherfunction(x, y) = x^2*y"]
    )

You can also define your own in julia/operators.jl, and pass the function name as a string. This is suitable for more complex functions. Make sure that it works with Float32 as a datatype. That means you need to write 1.5f3 instead of 1.5e3, if you write any constant numbers.

Your operator should work with the entire real line (you can use abs(x) - see logm); otherwise the search code will be slowed down with domain errors.