MaplePrimes - answers and comments on Question, computation of boolean operations

It is doubtful

hirnyk — Fri, 20 Aug 2010 22:28:48 Z

I have doubts of this. Here are three arguments:

> with(Bits): Xor(a, b) assuming a::integer, b::integer;
Error, (in assuming) when calling 'Bits:-Xor'. Received: 'argument 1, the first number,
must be an integer'
> MmaTranslator:-Mma:-Xor[x, y];
Error, Xor is not a command in the MmaTranslator:-Mma package

> MmaTranslator:-Mma:-BitXor(x, y);
Error, (in MmaTranslator:-Mma:-BitXor) Maple cannot handle the function BitXor with arguments (x, y)

Appendix. Having read the answer by John May, I suggest the following procedure:

> XOR := proc (a0, b0, a1, b1) with(Bits): Xor(a0*b1, a1*b0) end proc;
XOR:=proc(a0, b0, a1, b1) with(Bits); Xor(a0*b1, a1*b0) end proc;
> XOR(1, 2, 32, 43);
107

The bitwise Xor in the ?Bits package will

John May — Fri, 20 Aug 2010 22:48:24 Z

The bitwise Xor in the ?Bits package will complain if you don't give it integers. One solution would be to use the neutral operator &xor and then do a substitution when you are ready to evaluate:

(**) expr := (a1*b0) &xor (a0*b1);
#                           expr := a1 b0 &xor a0 b1

(**) expr2 := eval(expr, {a0=1,a1=32,b0=2,b1=43});
#                              expr2 := 64 &xor 43

(**) eval(expr2, `&xor` = Bits:-Xor);             
#                                      107

This form has the advantage that it can be manipulated by the ?Logic package as well (if that even makes sense for your application.

(**) Logic:-Normalize(expr);
#             (a0 b1 ∧ ¬(a1 b0)) ∨ (a1 b0 ∧ ¬(a0 b1))