Function builtin_sign 

fn builtin_sign(
    args: &[RValue],
    _: &[(String, RValue)],
) -> Result<RValue, RError>

Sign of each element (-1, 0, or 1).

R’s sign() returns 0 for zero inputs (unlike Rust’s f64::signum which returns 1.0). For integer inputs, returns an integer vector; for double inputs, returns a double vector.

@param x numeric vector @return numeric vector of signs