Re: [Gretl-devel] matrix transposition/multiplication operator precedence
Am 02.07.2016 um 19:45 schrieb Allin Cottrell:
On Sat, 2 Jul 2016, Riccardo (Jack) Lucchetti wrote:
> a'b'
>
> * is equivalent to (a') * (b') in Ox, Gauss and Julia
> * is illegal in Octave (which doesn't have, I think, the binary '
> operator)
>
> so we're the exception. So I guess it's just another case of choice
> between backward-compatibility and pragamtism.
I take the point here, but changing gretl's behavior in this regard will
not be trivial. Unary transpose is unique as an operator that appears to
the right of its operand, and we cannot in general tell unary transpose
from binary transpose-multiply without "look behind", which we don't
have in our parser at present.
I'll think about this some more, but I'm not going to attempt a change
before the forthcoming release.
Absolutely it's better not to rush it. About the "look behind" stuff I'm
not sure I understand. Currently I guess the parser already needs to
decide whether any "'" is unary or binary. Or do you mean that it's
always treated as binary unless the next thing is a closing parentheses
or the end of line? (Although even then the "next thing" situation would
imply some looking behind.)
thanks,
sven