Number protocol - Factor Documentation (original) (raw)
Math operations obey certain numerical upgrade rules. If one of the inputs is a bignum and the other is a fixnum, the latter is first coerced to a bignum; if one of the inputs is a float, the other is coerced to a float.
Two examples where you should note the types of the inputs and outputs:
USE: classes 3 >fixnum 6 >bignum * class-of .
bignum
1/2 2.0 + .
2.5
The following usual operations are supported by all numbers.
+ ( x y -- z ) - ( x y -- z ) * ( x y -- z ) / ( x y -- z )
Non-commutative operations take operands from the stack in the natural order; 6 2 / divides 6 by 2.
Division by zero
Real numbers (but not complex numbers) can be ordered:
<= ( x y -- ? ) > ( x y -- ? ) >= ( x y -- ? )
Numbers can be compared for equality using =, or a less precise test which disregards types: