[Octave-bug-tracker] [bug #33304] power operator precedence and direction

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?33304>

                 Summary: power operator precedence and direction
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Fri May 13 09:26:32 2011
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: pawel
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.4.0
        Operating System: Mac OS

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Details:

expression
> a^b^c
is evaluated from left to right as
> (a^b)^c
which is eqaul and could or even should be equivalent of
> a^(b*c)

however expression
> -a^-b^-c
is evaluated from right to left
> -a^(-b^-c)
which is not equal 
> -a^(-b*(-c))

i think it's serious inconsistency.

The case could be simpler if unary operator had higher priority then power,
hovewer i agree that -x^y = -(x^y).

I think that parser should follow semantic like:

unaryExpr:    (+|-|!)? powerExpr;
        
powerExpr:   atom (^ exp)*;

exp     :              (+|-|!)? atom;

atom:             ID | NUMBER | FUNCTION_CALL | ( expression )







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