BigInteger.isProbablePrime
For a large known prime b
, and for any certainty
, b.isProbablePrime(certainty)
returns true
.
isProbablePrime
can only err by returning true
when the input is not prime (an example is b=6
, certainty=0
, which returns true
), never the other way (because the Rabin-Miller test, which isProbablePrime
uses, can only fail in this direction).
For a large known prime, and for any certainty > 0, is it accurate to say that b.isProbablePrime(certainty) will always return true?
Yes. The documentation says it will return false
only if it is certain that the number is composite.
Returns: true if this BigInteger is probably prime, false if it's definitely composite.
So the certainty
parameter will influence only on the chance of a false-positive: saying a composite number is prime, when it really is not.