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Section: 29.4.8 [complex.transcendentals] Status: NAD Submitter: Matt Austern Opened: 2003-11-05 Last modified: 2016-01-28
Priority: Not Prioritized
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Discussion:
Operations like pow and exp on
complex<T> are typically implemented in terms of
operations like sin and cos on T.
Should implementations write this as std::sin, or as plain
unqualified sin?
The issue, of course, is whether we want to use
argument-dependent lookup in the case where T is a
user-defined type. This is similar to the issue of valarray
transcendentals, as discussed in issue 226(i).
This issue differs from valarray transcendentals in two important
ways. First, "the effect of instantiating the template
complex for types other than float, double or long double is
unspecified." (29.4.2 [complex.syn]) Second, the standard does not
dictate implementation, so there is no guarantee that a particular
real math function is used in the implementation of a particular
complex function.
Proposed resolution:
Rationale:
If you instantiate std::complex for user-defined types, all bets are off.