3.2 Multiplying uncertain values

$x = 1 +- 0.1;
$y = 2 +- 0.1;
calculate $x * $y;

Here we would expect the error in the result to be 2 * sqrt( (0.1/1)**2 + (0.1/2)**2), or 0.2236, according to the usual technique of error propagation. The result from Epc is

Result without perturbation: 2 Result with symmetric tails: 1.99977 +- 0.223437 Result with asymmetric tails: 1.99977 (1.78026 to 2.22714)

which agrees reasonably.