[ET Trac] [Einstein Toolkit] #624: Replace Cactus complex number implementation with C/C++ standard implementation

[Einstein Toolkit]

#624: Replace Cactus complex number implementation with C/C++ standard
implementation
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  Reporter:  eschnett     |       Owner:        
      Type:  enhancement  |      Status:  review
  Priority:  major        |   Milestone:        
 Component:  Cactus       |     Version:        
Resolution:               |    Keywords:        
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Changes (by eschnett):

  * status:  new => review


Comment:

 The enclosed patch changes the definition of CCTK_COMPLEX to use C99 or
 C++ complex datatypes, respectively. The Cactus complex number functions
 CCTK_Cmplx* are retained for compatibility, and only wrap the C99
 functions.

 In most places the changes are trivial.

 File cctk_Complex.h contained optimisations allowing inlining; since we
 are using different implementations in C and C++, this is not easily
 possible any more, and is now disable. (The inlining, that is.)

 In many places, real and imaginary parts were accessed as structure
 members. This is not possible any more, and has been replaced by calls to
 CCTK_Cmplx{Real|Imag}. This probably also teaches a lesson about the
 values of information hiding.

 In many places, complex numbers were explicitly treated as two-vector of
 real numbers. This is now not necessary any more, simplifying the code.

 Thorn LocalReduce is not amenable to modifications. I disabled it in this
 patch. A better solution is probably to remove support from complex
 numbers from it, since this support has serious errors anyway. In the long
 term, LocalReduce should be rewritten in C++, probably reducing code size
 by a factor of 100.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/624#comment:1>
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