On Mon, Sep 29, 2008 at 20:22, Charles R Harris <charlesr.harris@gmail.com> wrote:
On Mon, Sep 29, 2008 at 4:28 PM, Robert Kern <robert.kern@gmail.com> wrote:
On Mon, Sep 29, 2008 at 17:13, Charles R Harris <charlesr.harris@gmail.com> wrote:
On Mon, Sep 29, 2008 at 3:52 PM, Charles R Harris <charlesr.harris@gmail.com> wrote:
Hi All,
I've been cleaning up the ufunc loops and the sign function currently doesn't have a defined behavior for nans. This makes the results depend on the order/type of comparisons in the code, which looks fragile to me. So what should it return? I vote for nan but am open for suggestions.
And while we're at it, lets decide how to treat max/min when nans are involved. Or should we just say the behavior is undefined.
When feasible, I would like float(s)->float functions to return NaN when given a NaN as an argument. At least as the main versions of the function. Specific NaN-ignoring functions can also be introduced, but as separate functions. I don't know what exactly to do about float->int functions (e.g. argmin). I also don't know how these should interact with the current seterr() state.
OK, maximum, minimum, and sign now return NaN.
Oops! F.9.9.2 The fmax functions 1 If just one argument is a NaN, the fmax functions return the other argument (if both arguments are NaNs, the functions return a NaN). 2 The body of the fmax function might be {return (isgreaterequal(x, y) || isnan(y)) ? x : y; } If we want to follow C99 semantics rather than our own NaN-always-propagates semantics, then we should do this instead. -- Robert Kern "I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco