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From: Dave Steffen (dgsteffen_at_[hidden])
Date: 2007-12-18 16:58:58

On Monday 17 December 2007, Kevin Lynch wrote:
> Andreas Harnack wrote:
> > If you think that this doesn't belong to the standard, then
> > please allow me to ask one question: Why is there a complex
> > number class in the standard and what does it actually do?
> There are a number of fundamental differences: the operations on
> complex numbers provided for in the standard covers exactly the same
> domain of tasks as are covered by the built-in floating point types.
> Standardization is possible because implementing those operations for
> complex in a numerically stable and efficient way is relatively simple
> (although even that can go astray pretty rapidly), and the "best"
> storage format of complex numbers on the hardware has long been well
> understood and agreed upon. Even the class interface can be agreed upon
> pretty trivially, and with minimal impact on implementation flexibility.

  Right. In addition, there is a precedent, in that Fortran supports
  complex number types natively. They're not uncommon in numerical
  code, and fairly easy to get right (and to get people to agree on
  the interface).

  Note, however, that nobody ever tries to standardize what
  sqrt(complex) means, because that's a vastly more compex problem
  (pun intended), and because people who need that sort of thing will
  go find a specialized library that supports it.


Dave Steffen - Software Engineer 4
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