Re: BLAS (was Matlisp tests)

On 3/13/12 9:45 AM, Akshay Srinivasan wrote:
> On 03/12/2012 12:18 AM, Raymond Toy wrote:
>> On 3/11/12 11:11 AM, Akshay Srinivasan wrote:
>>> On 03/11/2012 12:37 PM, Raymond Toy wrote:
>>>> On 3/10/12 7:03 PM, Akshay Srinivasan wrote:
>>>>> On 03/10/2012 11:16 PM, Raymond Toy wrote:
>>>>>> On 3/10/12 8:40 AM, Akshay Srinivasan wrote:
>>>>>>
>>>>>>>> It would be nice to be able to detect either mode and
>>>>>>>> have the ffi do the right thing, but I think many lisps
>>>>>>>> do not support structure returns the way gcc is doing
>>>>>>>> it now.
>>>>>>> It returns a struct ? I never could get hold of the 
>>>>>>> documentation for that.
>>>>>> That's my understanding.  And when I look at the
>>>>>> disassembly for a simple Fortran function, it returns the
>>>>>> real and imaginary parts in xmm0 and xmm1 (at least on
>>>>>> OSX).
>>>>> Hmm. Too clumsy and non-portable to support all that, no ?
>>>> It would be good if cffi supported that, but I suspect not.
>>>>>>>> We also have an alternative: Add simple C wrappers
>>>>>>>> that use the f2c-mode return and call the Fortran
>>>>>>>> routine directly.
>>>>>>> CBLAS :) (not the netlib version).
>>> After some more thinking, I vote for adding wrapper subroutine
>>> around zdotu/zdotc in F77. It'll be far too much boring work to
>>> migrate to CBLAS, given that I seem to be able to handle ordering
>>> quite well within lisp itself. There aren't any other complex
>>> returning functions in BLAS, are there ?
>> Let me do a grep....Nope.  Looks like those are the only two.
>>
>> Not quite sure what you're going to do here.  You want to write two
>> C wrapper functions that call zdotu/zdotc correctly, and have the
>> wrapper use the f2c convention?
>>
>> Since we already detect if we need -ff2c, what is the utility for
>> this when matlisp builds its own libraries?  Of course, for atlas,
>> I can see that we would want this if we've determined that atlas is
>> not compatible.  That would be a nice enhancement.
>>> We probably don't need any other f2c features, since most
>>> functions I know only take character arguments instead of string
>>> ones.
>> Fortunately, matlisp is in control of that because I think it is
>> valid fortran to pass in, say, 'Transpose', instead of 'T'.
> I have to flip back on my words. I now think CBLAS is the only way
> forward. I was writing a wrapper for dgemv (y <- alpha * A . x + beta
> y) today and really couldn't figure out a way to support row-ordered

Can you give an example?  You can't just transpose A?  Oh.  Maybe not
because the elements still need to be in column-major order?

Ray


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