A draft for a SymPy CCode op is here https://github.com/Theano/Theano/pull/1486
On Thu, Aug 8, 2013 at 10:20 PM, Frédéric Bastien <no...@nouiz.org> wrote: > For your codegen.py example, it is easy to reuse it manually in a Theano > Op. A good example is to look at the GpuEye op (and just pretend the the > GPU kernel is a CPU one). I don't know of a simpler CPU example that > demonstrate that: > > > https://github.com/Theano/Theano/blob/master/theano/sandbox/cuda/basic_ops.py#L3421 > > You put the c function in c_support_code() function and call it with code > returned by the c_code() fct. > > If we want to automate that, we need a way to know the order of the > parameter passed to the c function if there is more then 1 parameter. Is > that possible? Ideally, we need to separate the include from the c > function, but I think it work even if we don't. > > About the Theano speed up, the problem is located in the parsing of the > Theano fct inputs. This is done in pure python code. I think we can always > use the trust_input=True argument. In the case there is an error, you will > get an error message that is harder to understands, as it is an op that > will complain that it have bad input. But you won't be easily able to know > to witch input it correspond. > > It could also happen that you don't pass a good input and there is no > error. For example if it is used in an op with only python code. But in > that case, the computation is probably done correctly, but with the input > object received, not the one specified when compiling the theano function. > I can't certify this always happen, but I would be surprised to see > something else being done. > > So if you want, just always add trust_input=True, but be ready to have > uglier error message and remove the flag to have a better error message in > case you have a problem. > > Ideally, Theano should move that to C code, but I don't think it will > happen shortly. > > > On Thu, Aug 8, 2013 at 7:27 PM, Matthew Rocklin <mrock...@gmail.com>wrote: > >> @Fred, what easy things can we do on the Theano side to support >> performant scalar codes? Your two tricks above were impressive. How can >> we make this behavior default? Should this happen on the SymPy side or the >> Theano side (Theano side seems better if there is a place for it). >> >> >> On Thu, Aug 8, 2013 at 4:05 PM, Aaron Meurer <asmeu...@gmail.com> wrote: >> >>> >>> >>> On Thursday, August 8, 2013, Matthew Rocklin wrote: >>> >>>> >>>> It should be simple to translate SymPy.Piecewise to a recursive >>>>>> Theano.switch (after translating SymPy.LT to theano.lt, etc.) I'll >>>>>> get on this soon. Does this sound reasonable to you Fred? >>>>>> >>>>> >>>>> It sound reasonable and is the first thing I suggest to try. >>>>> >>>> >>>> Working on this now. >>>> >>>> > SymPy C Codegen and Theano >>>>>> >>>>>> @Fred, how hard would it be to leverage SymPy's C codegen in Theano? >>>>>> This might be a lot cleaner than wrapping raw SymPy operations and might >>>>>> substantially extend Theano's support of scalar expressions. Do you >>>>>> have a >>>>>> performant Bessel function op? I'll bet SymPy could be made to do this >>>>>> quite well. >>>>>> >>>>>> @Aaron / @Ondrej, if you're reading this thread could you point us to >>>>>> the best place to start looking at C codegen in SymPy? Alternatively can >>>>>> you point to an active community member who would be able to do so? >>>>>> >>>>>> >>>>> @Matt, you already did a new Theano op with C code. I think it is the >>>>> only "easy" way to wrap other people c code in Theano. If the person >>>>> already know this C code AND a little of Python AND NumPy C-API, it isn't >>>>> very hard to a new Theano op with C code. Otherwise, doing the first such >>>>> op ask to learn a few think and could ask a few days. You already did >>>>> this, >>>>> so you have a good idea of the work it need. >>>>> >>>>> Now the questions is how is done the SymPy code gen? Is just just >>>>> string template that is filled with dtype and other stuff? If we can just >>>>> call one SymPy function with the information of what we want and it return >>>>> a string with the C code it could be relatively easy. The only questions >>>>> is >>>>> about how to handle the variable name to pass the information around. At >>>>> worst, we wrap the sympy c code in a c function, then make a small wrapper >>>>> c code that take the Theano c variable name and call this function. So not >>>>> very hard as Theano provide what is needed. >>>>> >>>> >>>> It looks like codegen is the relevant high-level api call >>>> >>>> In [1]: from sympy.utilities.codegen import >>>> >>>> In [2]: expr = sin(x)**2 >>>> >>>> In [3]: [(c_name, c_code), (h_name, c_header)] = codegen(("f", expr), >>>> 'C', 'test', header=False) >>>> >>>> In [4]: print c_code >>>> #include "test.h" >>>> #include <math.h> >>>> >>>> double f(double x) { >>>> >>>> return pow(sin(x), 2); >>>> >>>> } >>>> >>>> The work I did rarely dealt with making and using functions. I'll go >>>> over past work and see what I can do. Expect some calls for help though! >>>> >>> >>> If you figure out how to do something that's under-documented, please >>> document it. Our code generation needs a lot more documentation, especially >>> high-level narrative documentation. >>> >>> Aaron Meurer >>> >>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "sympy" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to sympy+unsubscr...@googlegroups.com. >>>> To post to this group, send email to sympy@googlegroups.com. >>>> Visit this group at http://groups.google.com/group/sympy. >>>> For more options, visit https://groups.google.com/groups/opt_out. >>>> >>>> >>>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "sympy" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to sympy+unsubscr...@googlegroups.com. >>> To post to this group, send email to sympy@googlegroups.com. >>> Visit this group at http://groups.google.com/group/sympy. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sympy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to sympy+unsubscr...@googlegroups.com. >> To post to this group, send email to sympy@googlegroups.com. >> Visit this group at http://groups.google.com/group/sympy. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sympy+unsubscr...@googlegroups.com. > To post to this group, send email to sympy@googlegroups.com. > Visit this group at http://groups.google.com/group/sympy. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out.
