[petsc-users] matrix with complex number

[Hal Finkel]

Barry,

I've used the following process to achieve a similar effect in C projects:

Modify the make files to build each source file multiple times, once for 
each base type (float, double, double complex, etc.). The type is 
selected via a preprocessor definition provided on the command line 
(-DUSE_FLOAT, -DUSE_DOUBLE, etc.). A prefix or suffix specific to each 
type is appended to the name of the resulting object file (so that 
they're unique). Also, the function names (and all other global symbols) 
in each file are wrapped with a function-like macro which appends a 
prefix or suffix depending on the current type selected. In this way, 
everything can be included in one library without conflict or 
unnecessary code duplication.

  -Hal

Barry Smith wrote:
> 
>    The issue is that PETSc is written in C and there are not C++ 
> templates in C. We do not want to write TWO copies of each file, one 
> with dcomplex everywhere and another with double everywhere and give 
> different names to the functions in each language. It would be a pain to 
> write and maintain and a pain to use. Who wants to write MatSolve() to 
> solve with real numbers and MatSolveComplex() to solve with complex?
> 
>   C++ templates can be used to make all this possible but they are not 
> perfect to the task. Basically we need a better language to allow easy 
> mixing of dcomplex and double.
> 
>    Barry
> 
> 
> 
> On Jan 22, 2010, at 2:43 PM, Yujie wrote:
> 
>> Dear Barry,
>>
>> What are the difficult things if PETSc is revised with matrices of 
>> complex and real numbers? It should be more flexible for a general 
>> scientific toolbox. I am curious almost all the packages don't support 
>> both simultaneously. Thanks a lot.
>>
>> Regards,
>> Yujie
>>
>> On Fri, Jan 22, 2010 at 2:35 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>
>>   The way we handle complex numbered linear systems in PETSc is to 
>> compile all of PETSc with complex numbers and then just use the 
>> solvers on those complex numbers. The current drawback to this is that 
>> PETSc can only be built with support for complex numbers or for real 
>> numbers. We cannot build a PETSc where some matrices are complex and 
>> some are real.
>> We don't have any interest in solving complex systems as larger real 
>> systems.
>>
>>   Barry
>>
>>
>> On Jan 22, 2010, at 11:04 AM, Yujie wrote:
>>
>> Dear PETSc Developers,
>>
>> Recently, I am trying to find some complex number-based solvers and 
>> preconditioners. However, it is difficult to find a general framework 
>> to include some solvers and preconditioners. Trilinos is developing a 
>> package, komplex, to use the real-number-based solver to solve complex 
>> number -based problem. I don't know whether PETSc wants to develop 
>> such the function for complex number-based problem. I think it will 
>> significantly increase the application range of PETSc. After all, in 
>> PETSc, lots of solvers and preconditioners have been developed. 
>> Thanks  a lot.
>>
>> Regards,
>> Yujie
>>
>>