Cargo Features

[dependencies]
approx = { version = "0.5.1", default-features = false, features = ["std", "num-complex"] }
default = std

The std feature is set by default whenever approx is added without default-features = false somewhere in the dependency tree.

std default

Features from optional dependencies

num-complex implicit feature

Enables num-complex

num-complex:

Complex numbers implementation for Rust