All FFT's need double precision - not

Article: PhysX87: Software Deficiency
By: Vincent Diepeveen (diep.delete@this.xs4all.nl), July 24, 2010 11:19 pm
Room: Moderated Discussions
Michael S (already5chosen@yahoo.com) on 7/20/10 wrote:
---------------------------
>Vincent Diepeveen (diep@xs4all.nl) on 7/19/10 wrote:
>---------------------------
>>David Kanter (dkanter@realworldtech.com) on 7/19/10 wrote:
>>---------------------------
>>
>>All FFT's need double precision or integer transforms. To build it in single precision
>>ain't easy, to say polite. Overflow here, overflow there, round off error here, round off error there.
>>
>
>Sound like a bullsheet.
>
>Of course, nearly all FFTs used in signal processing (spectrum estimation, FIR
>filtering, crosscorrelation etc) are fine with single precision. In fact, in majority
>of cases 24-bit mantissa is an overkill. HiFi audio is the only notable exception I could think about.
>For image compression/expansion precision requirements of FFT/DCT are lower yet.
>I'd assume that for object recognition, motion estimation and similar fields (variants
>of 2D xcorr) single-precision FFT is also more than fine.
>

Michael,

You're describing a few calculations that eat very little system time compared to the guys needing double precision.

Matrix calculations and similar calculations, they eat vaste majority all system time of HPC hardware, and have a hunger of far more system time.

Please note that in the commercial sector, most system time goes to safety calculations (car industry, air industry), which is for biggest part of the calculations also double precision calculations.

Those who can run single precision there, are already running single precision there at GPU's for years of course.

Thanks,
Vincent
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            You are just quoting SINGLE precision flops? OMG what planet do you live? Vincent Diepeveen2010/07/19 10:26 AM
              The prior poster was talking about SP (NT)David Kanter2010/07/19 11:34 AM
                All FFT's need double precisionVincent Diepeveen2010/07/19 02:02 PM
                  All FFT's need double precisionDavid Kanter2010/07/19 02:09 PM
                    All FFT's need double precisionVincent Diepeveen2010/07/19 04:06 PM
                  All FFT's need double precision - notMichael S2010/07/20 01:16 AM
                    All FFT's need double precision - notUngo2010/07/21 12:04 AM
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                      All FFT's need double precision - notEduardoS2010/07/21 02:52 PM
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                        All FFT's need double precision - notVincent Diepeveen2010/07/24 11:39 PM
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                            All FFT's need double precision - notRicardo B2010/07/26 07:40 AM
                          All FFT's need double precision - notEduardoS2010/07/25 08:37 AM
                            All FFT's need double precision - notMichael S2010/07/25 10:43 AM
                    All FFT's need double precision - notVincent Diepeveen2010/07/24 11:19 PM
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            All right...let's cool it...David Kanter2010/07/08 07:54 PM
    A bit off baseVincent Diepeveen2010/07/19 03:36 PM
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