http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24581
--- Comment #20 from marco atzeri <marco_atzeri at yahoo dot it> 2010-11-22 14:17:24 UTC --- (In reply to comment #19) > On Mon, 22 Nov 2010, sgk at troutmask dot apl.washington.edu wrote: > > > That -nan is not an infinity is true but irrelevant, because "A complex or > imaginary value with at least one infinite part is regarded as an infinity > (even if its other part is a NaN)." (G.3), so the complex result of the > multiplication *is* an infinity (with one part NaN and one part infinity, > which is a valid representation of complex infinity). I guess that I was misleaded by the status FIXED. Following your reasoning INVALID or WONTFIX are probably more accurate STATUS as the behaviour is not a BUG but a possible implementation. As 0 * Inf = NaN on real/double, it follows that for complex ( 0 + I ) * Inf = 0 * Inf + I * Inf = NaN + I * Inf however the implementation is not symmetric as ( 1 + I*0) * Inf = Inf + 0 * I Of course (Inf + 0 * I) and (NaN + I * Inf) are both complex infinities, but the lack of symmetry is inelegant ;-) The table at C99 G.5.1-2 seems to suggest a symmetric behaviour, of course IMHO
