dolfin team mailing list archive

[Evan Lezar <evanlezar@xxxxxxxxx>]

On Fri, Feb 27, 2009 at 5:20 PM, Garth N. Wells <gnw20@xxxxxxxxx> wrote:

>
>
> Martin Sandve Alnæs wrote:
>
>> On Fri, Feb 27, 2009 at 4:08 PM, Garth N. Wells <gnw20@xxxxxxxxx> wrote:
>>
>>>
>>> Martin Sandve Alnæs wrote:
>>>
>>>> On Fri, Feb 27, 2009 at 4:03 PM, Garth N. Wells <gnw20@xxxxxxxxx>
>>>> wrote:
>>>>
>>>>> Evan Lezar wrote:
>>>>>
>>>>>> Hi
>>>>>>
>>>>>> I am working on some electromagnetic problems that require I model the
>>>>>> electric field as a complex phasor.  When compiling user-defined
>>>>>> functions I get an error message.
>>>>>>
>>>>>> For example, consider the following simple function:
>>>>>>
>>>>>> f = Function(V, '1.0j')
>>>>>>
>>>>>>
>>>>>> when calling the JIT compiler, the log shows the following error (in
>>>>>> the
>>>>>> last couple of lines):
>>>>>>
>>>>>> dolfin_compile_function_934f16b21b1210d9244eba2ba7985a9a_wrap.cxx: In
>>>>>> member function ‘virtual void
>>>>>> dolfin::function_91ee55df622466fafbf3ba887ffb745e::eval(double*, const
>>>>>> double*) const’:
>>>>>>
>>>>>> dolfin_compile_function_934f16b21b1210d9244eba2ba7985a9a_wrap.cxx:3221:
>>>>>> error: cannot convert ‘double __complex__’ to ‘double’ in assignment
>>>>>> error: command 'gcc' failed with exit status 1
>>>>>>
>>>>>> Does dolfin support complex valued functions?
>>>>>>
>>>>> No.
>>>>>
>>>>> If so, how do I go about
>>>>>
>>>>>> getting them working?  And if not, how do I go about adding the
>>>>>> functionality.
>>>>>>
>>>>>>  It would be a big task to make it seamless. The starting point would
>>>>> be
>>>>> having FFC (or soon UFL) support complex functions. I thought about
>>>>> this
>>>>> a few years ago but never got around to it.
>>>>>
>>>>>  Thinking about, it shouldn't be too hard to patch something together
>>> using
>>> mixed elements.
>>>
>>
>> Won't be as user-friendly as it could be though, but perhaps you
>> could define e.g. complex multiplication as python functions on top.
>>
>>
> Agree, it wouldn't be user friendly. Making it user friendly would require
> a lot of work on UFL/FFC/DOLFIN.
>
> Garth
>
>
>
>
>>  UFL question: Does or will UFL support complex functions?
>>>>>
>>>> No. And I don't think making such an addition before it has stabilised
>>>> is an option, we can't change everything everywhere simultaneously.
>>>>
>>>>  OK. Would be good for the long-term goals list.
>>>
>>
>> Sure. I'll add it.
>>
>> Martin
>>
>
>
>
Thanks for the feedback.  I have got some ideas for an interim solution,
will give them a go and let you know what I come up with.

Evan