
plus(?Add1, ?Add2, ?Sum)

   Succeeds if Sum is the sum of integer arguments Add1 and Add2.



Arguments
   Add1                an integer or a variable
   Add2                an integer or a variable
   Sum                 an integer or a variable

Type
   Arithmetic

Description
   Defines the arithmetic relation Add1 + Add2 = Sum.  If all arguments are
   instantiated plus/3 succeeds if this relation holds.  If one of the
   arguments is uninstantiated, it is bound to an integer such that the
   relation holds.  If the system is in coroutining mode and more than one
   argument is uninstantiated, plus/3 delays until at least two of the
   arguments are known.




Modes and Determinism
   plus(+, +, -) is det
   plus(+, -, +) is det
   plus(-, +, +) is det

Exceptions
     5 --- an argument is neither an integer nor a variable
     4 --- more than one argument is uninstantiated (non-coroutining    mode only)

Examples
   
   Success:
   plus(1, 2, 3).
   plus(3, 4, Z).                   (gives Z=7)
   plus(X, 4, 7).                   (gives X=3)
   plus(3, Y, 7).                   (gives Y=4)
   Fail:
   plus(3, 4, 5).
   Error:
   plus(3.0, 4.0, 7.0).             (error 5)
   plus(2 + 3, 1, 6).               (error 5)
   plus(X, 1, Z).                   (error 4)





See Also
   times / 3
