Function std::intrinsics::copysignf64

pub unsafe extern "rust-intrinsic" fn copysignf64(x: f64, y: f64) -> f64

Unstable (core_intrinsics #0)

: intrinsics are unlikely to ever be stabilized, instead they should be used through stabilized interfaces in the rest of the standard library

Copies the sign from y to x for f64 values.