Numeric comparison implies subtraction or similar a - b sign and zero extraction at some lower level (in an ALU micro-op perhaps), so that's duplicated effort o

Numeric comparison implies subtraction or similar a - b sign and zero extraction at some lower level (in an ALU micro-op perhaps), so that's duplicated effort of a - b unless it can be optimized away. match a - b { d if d >= 0.0 => d < f64::EPSILON, d => d >= -f64::EPSILON, /* true if -EPSILON to -0.0 */ } https://godbolt.org/z/71PGzd7oa https://godbolt.org/z/71PGzd7oa