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Thread: confuse with floating point type in OpenVG specification.

  1. #1

    confuse with floating point type in OpenVG specification.

    dear all:
    in OpenVG spec. page 8(page 18 in PDF reader)
    " ...at least 16 bits mantissa, and 6 bits for exponent....."

    but in OpenVG page 9 (page 19 in PDF reader)
    ".. all implement must define VG_MAX_FLOAT to be at least 10^10..."

    the precision s6.16 can not represent 10^10 correctly.....
    so strange.

  2. #2
    Senior Member
    Join Date
    May 2006
    Posts
    353
    Hm, it's close: 10^10 is 2^33.2, while a s16e6 number with exponent biased by 31 can represent 1.999 * 2^32.
    So you either need to increase the bias by one or use a wider exponent. But I guess the intention was to allow s16e7, i.e. 24 bit floating point. 23 bit numbers seem quite odd.
    Georg Kolling, Imagination Technologies
    Please ask questions specific to PowerVR hardware or SDKs on the PowerVR Insider Forum
    DevTech@imgtec.com | http://www.powervrinsider.com

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