This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: __builtin_cpow((0,0),(0,0))
- From: Gabriel Dos Reis <gdr at integrable-solutions dot net>
- To: Paul Schlie <schlie at comcast dot net>
- Cc: <gcc at gcc dot gnu dot org>
- Date: 13 Mar 2005 05:53:34 +0100
- Subject: Re: __builtin_cpow((0,0),(0,0))
- Organization: Integrable Solutions
- References: <BE58A7CA.96F5%schlie@comcast.net>
Paul Schlie <schlie@comcast.net> writes:
[...]
| > You've transmuted the function x^y to the function x^x which is a
| > different beast. Existing of limit of the latter does not imply
| > existance of limit of the former. Again check the counterexamples in
| > the message I referred to above.
|
| Thank you. In essence, I've intentionally defined the question of x^y's
| value about x=y->0 as a constrained "bivariate" function, to where only
| the direction, not the relative rate of the argument's paths are ambiguous,
| as I believe that when the numerical representation system has no provision
| to express their relative rates of convergence, they should be assumed to be
| equivalent;
You're seriously mistaken. In lack of any further knowledge, one should not
assume anything particular. Which is reflected in LIA-2's rationale.
You just don't know anything about the rate of the arguments.
| as the question of a functions value about any static point such
| as (0,0) or (2,4) etc., is invalid unless that point is well defined within
| it's arguments path; where if it is, then the constrained representation is
| equally valid, but not otherwise (as nor is the question).
|
| Therefore in other words, the question of an arbitrary function's value
| about an arbitrary static point is just that, it's not a question about a
| functions value about an arbitrary point which may or may not be intersected
| by another function further constraining it's arguments.
|
| Therefore the counter argument observing that x^y is ambiguous if further
| constrained by y = k/ln(x), is essentially irrelevant; as the question is
That was just *one* set of counterexample. It is very relevant to
the complexity of the issue.
| what's the value of x^y, with no provision to express further constraints
| on it's arguments. Just as the value of (x + y) if further constrained by
| y = x, about the point (1,2) would be both ambiguous and an irrelevant to
| the defined value of (x + y) about (1,2).
You comparing apple and oranges. "+" is continuous at any point. "^"
is not. That is the core issue.
-- Gaby