Multiplication of a real number by -1 occurs on a general basis, no faster than by an arbitrary number?

Question

Programming

There are many multiplications of double numbers by -1 in the algorithm, in fact, you only need to change the sign. Multiplication of a real number by -1 occurs on a general basis, no faster than by an arbitrary real number? If so, is it possible to change the sign somehow more economically?

Answer 1

Practice here or here .
You can simply invert the most significant bit.

Answer 2

There are many multiplications of double numbers by -1 in the algorithm, in fact, you only need to change the sign.

If only multiplication, then multiply positive integers, and count the sign at the very end through an even / odd number of factors: even - "+", odd - "-".