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Re: Fix yn overflow handling in non-default rounding modes (bug 16561, bug 16562)

On 06/24/2014 01:35 AM, Joseph S. Myers wrote:
> This patch fixes bugs 16561 and 16562, bad results of yn in overflow
> cases in non-default rounding modes, both because an intermediate
> overflow in the recurrence does not get detected if the result is not
> an infinity and because an overflowing result may occur in the wrong
> sign.  The fix is to set FE_TONEAREST mode internally for the parts of
> the function where such overflows can occur (which includes the call
> to y1 - where yn is used to compute a Bessel function of order -1,
> negating the result of y1 isn't correct for overflowing results in
> directed rounding modes) and then compute an overflowing value in the
> original rounding mode if the to-nearest result was an infinity.
> Tested x86_64 and x86 and ulps updated accordingly.  Also tested for
> mips64 and powerpc32 to test the ldbl-128 and ldbl-128ibm changes.

 Andreas Jaeger aj@{,} Twitter/Identica: jaegerandi
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