define abs(x) { if (x < 0) x *= -1 return x } define fact(x) { auto r if (x < 0) { print "Error: Negative factorial\n" return 0 } if (x % 1 != 0) { print "Error: Non-integer factorial\n" return 0 } r = 1 for (i = 2; i <= x; i++) r *= i return r }