[Numpy-discussion] Numeric/numarray compatibility issue
jmiller at stsci.edu
Fri Mar 4 11:44:40 EST 2005
On Fri, 2005-03-04 at 13:50, Perry Greenfield wrote:
> On Mar 4, 2005, at 1:24 PM, konrad.hinsen at laposte.net wrote:
> > What is actually the difference between Bool and Int8?
> I'm not sure I remember all the differences (Todd can add to this if he
> remembers better). Booleans are treated differently as array indices
> than Int8 arrays are. The machinery of generating Boolean results is
> different in that it forces results to be either 0 or 1.
Conversions to Bool, logical operations, and (implicitly) comparisons
constrain values to 0 or 1.
> In other
> words, Boolean arrays should only have 0 or 1 values in those bytes
> (not that it isn't possible for someone to break this in C code or
> though undiscovered bugs. Ufuncs that generate different values such as
> arithmetic operators result in a different type.
More general arithmetic appears to have unconstrained results.
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