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Subnormal floating-point numbers are expensive on Intel processors

69 points · 54 comments · zdw

  1. cesaref · · focus · HN ↗
    It used to be quite normal to add a low level random signal to inputs when writing DSP code so as to avoid dropping into subnormal territory. Careful analysis of the algorithm would identify any points where this was also necessary (e.g. feedback paths when running delays).

    Obviously those lucky/unlucky enough to be writing 56k fixed precision code wouldn't have this concern, but other ones instead :)

    I think flush to zero is probably the preferred strategy these days.

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