~ ( x y epsilon -- ? ) (original) (raw)
~ ( x y epsilon -- ? )
Factor handbook » The language » Numbers » Mathematical functions » Arithmetic functions
| Prev: | round-to-step ( x step -- y ) |
|---|
Inputs
| x | a real |
|---|---|
| y | a real |
| epsilon | a real |
Outputs
| ? | a boolean |
|---|
Word description
Tests if x and y are approximately equal to each other. There are three possible comparison tests, chosen based on the sign of epsilon:
| • | epsilon is zero: exact comparison. |
|---|---|
| • | epsilon is positive: absolute distance test. |
| • | epsilon is negative: relative distance test. |
Definition
USING: combinators kernel math ;
: ~ ( x y epsilon -- ? )
{
{ [ dup zero? ] [ drop number= ] }
{ [ dup 0 < ] [ neg ~rel ] }
[ ~abs ]
} cond ;