[Numpy-discussion] Draft PEP for the new buffer interface to be in Python 3000
Tue Feb 27 22:38:55 CST 2007
Charles R Harris wrote:
> The problem is that we aren't really specifying floating-point
> standards, we are specifying float, double and long double as whatever
> the compiler understands.
> There are some platforms which don't follow the IEEE 754 standard.
> This format specification will not be able to describe
> platform-independent floating-point descriptions.
> It would be nice to have such a description, but that is not what
> struct-style syntax does. Perhaps we could add it in the
> but I'm not sure if the added complexity is worth holding it up over.
> True enough, and it may not make that much sense until it is in the c
> standard. But it might be nice to reserve something for the future and
> maybe give some thought of how to deal with new data types as they
> come along. I can't think of any really flexible methods that don't
> require some sort of verbose table that goes along with the data, and
> the single letter codes are starting to get out of hand. Hmmm. It
> would actually be nice to redo things so that there was a prefix, say
> z for complex, f for float, then something for precision. The
> designation wouldn't be much use without some arithmetic to go with it
> and it doesn't make sense to write code for things that don't exist. I
> wonder how much of the arithmetic can be abstracted from the data type?
I suspect we may have to do this separately in the NumPy world.
Perhaps we could get such a specification into Python itself, but I'm
not hopeful. Notice, though that we could use the struct syntax to
specify a floating-point structure using the bit-field and naming.
In other words an IEEE 754 32-bit float would be represented in
struct-style syntax as
'>1t:sign: 8t:exp: 23t:mantissa:'
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