On 10/18/06, Tim Hochberg <[EMAIL PROTECTED]> wrote:
OK, that is good. I no longer have any objection to the flags, I just wish the names were more descriptive of what they mean. In fact, it looks like the following sort of construction will be useful in the linalg module.
In [17]:a = array([[1,2],[3,4]], dtype=int)
In [18]:b = array(a, dtype=double, order='f')
In [19]:b.flags
Out[19]:
CONTIGUOUS : False
FORTRAN : True
OWNDATA : True
WRITEABLE : True
ALIGNED : True
UPDATEIFCOPY : False
I've been a pain in the a** because I really want to know what is going on down in the boiler room.
Chuck
Charles R Harris wrote:
>
>
> On 10/18/06, *Tim Hochberg* <[EMAIL PROTECTED]
> <mailto:[EMAIL PROTECTED] >> wrote:
>
> Charles R Harris wrote:
>
> [SNIP]
> >
> > I'm not talking about the keyword in the ravel call, I'm talking
> about
> > the flag in a. The question is: do we *need* a fortran flag. I am
> > argueing not, because the only need is for fortran contiguous
> arrays
> > to pass to fortran function, or translation from fortran contiguous
> > arrays to numpy arrays. What I am saying is that things are
> > unnecessarily complicated. None of the LaPack stuff seems to use
> the
> > Fortran stuff, they just transpose and copy. I don't even think
> I want
> > to change that, because it is *clear* what is going on.
> Interfacing to
> > fortran is all about memory layout, nothing more or less.
> >
>
> Chuck,
>
> There are two things here. One is the order keyword and one is the
> FORTRAN flag. The latter is mainly an optimization for use at the
> C-level so that one doesn't have to check whether a given array is in
> contiguous FORTRAN order by examining the strides, in the same way
> that
> the CONTIGUOUS flag allows you to skip examining the strides when you
> need a contiguous C-order matrix.
>
>
> That sounds like the two flags should be named f-contiguous and
> c-contiguous. Then they would be orthogonal and one could have all
> four combinations. Is that the case now? Perhaps I am misunderstanding
> the meaning of the flags.
That is the case now. The flag names simply mirror their values in C.
Why they have those names in something of a historical accident I
believe. Take a look at this:
OK, that is good. I no longer have any objection to the flags, I just wish the names were more descriptive of what they mean. In fact, it looks like the following sort of construction will be useful in the linalg module.
In [17]:a = array([[1,2],[3,4]], dtype=int)
In [18]:b = array(a, dtype=double, order='f')
In [19]:b.flags
Out[19]:
CONTIGUOUS : False
FORTRAN : True
OWNDATA : True
WRITEABLE : True
ALIGNED : True
UPDATEIFCOPY : False
Chuck
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