▄▄▄▄▄▄▄
▌abs, ▐
▌cabs, cabsl,▐
▌fabs, fabsl,▐
▌labs ▐
▀▀▀▀▀▀▀▀▀▀▀▀▀▀
■ abs (a macro) gets the absolute value of an integer
■ cabs and cabsl (macros) calculate the absolute value of a complex number
■ fabs and fabsl calculate the absolute value of a floating-point number
■ labs calculates the absolute value of a long number