[Numpy-discussion] Time for beta1 of NumPy 1.0
David M. Cooke
cookedm at physics.mcmaster.ca
Fri Jun 30 13:59:28 CDT 2006
On Fri, 30 Jun 2006 14:42:33 -0400
"Jonathan Taylor" <jonathan.taylor at utoronto.ca> wrote:
> +1 for some sort of float. I am a little confused as to why Float64
> is a particularly good choice. Can someone explain in more detail?
> Presumably this is the most sensible ctype and translates to a python
> float well?
It's "float64", btw. Float64 is the old Numeric name.
Python's "float" type is a C "double" (just like Python's "int" is a C
"long"). In practice, C doubles are 64-bit.
In NumPy, these are the same type:
float32 == single (32-bit float, which is a C float)
float64 == double (64-bit float, which is a C double)
Also, some Python types have equivalent NumPy types (as in, they can be used
interchangably as dtype arguments):
int == long (C long, could be int32 or int64)
float == double
complex == cdouble (also complex128)
Personally, I'd suggest using "single", "float", and "longdouble" in numpy
code.
[While we're on the subject, for portable code don't use float96 or float128:
one or other or both probably won't exist; use longdouble].
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