abs_3 takes the absolute value of x. Equivalent to x=x<0?-x:x.
RETURN VALUE
inc_3, dec_3, negate_3 and abs_3 all return a pointer
to x which has been updated in place.
EXAMPLES
Some unary arithmetic operations on triple-ints:
unsigned x[3];
assign_int_3(x, 44);
negate_3(x); /* x is now -44 */
inc_3(x); /* x is now -43 */
abs_3(x); /* x is now 43 */
dec_3(x); /* x is now 42 */