Unix Version 7 - man page for abs (v7 section 3)

ABS(3)				     Library Functions Manual				   ABS(3)

NAME
       abs - integer absolute value

SYNOPSIS
       abs(i)

DESCRIPTION
       Abs returns the absolute value of its integer operand.

SEE ALSO
       floor(3) for fabs

BUGS
       You get what the hardware gives on the largest negative integer.

											   ABS(3)