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Re: converting ieee-float-format to pw-wave-float-format [message #2745 is a reply to message #2655]

Fri, 26 August 1994 05:47

grunes
Messages: 68
Registered: September 1993

Member

In article <33k7s5$972@elna.ethz.ch> SLAMECZKA@EZINFO.VMSMAIL.ETHZ.CH (SLAMECZKA,MICHAEL) writes:
> Now what is this IEEE format?
> Which bits are the exponent, which are the mantisse and how to translate it
> to pw_wave??

Be clear on one thing: there is no IDL or PV-Wave floating point format,
when used with readu and writeu.

They use what ever is normal for their machines. i.e.--if you read it
back on the same computer that you wrote it on, everything would
be fine.

I don't recall the exact format, but on a MSB first machine I
believe the order is:
Sign Bit (NOT twos complement format)
Base 2 exponent, excess notation
Mantissa, with assumed (not present) leading 1 (except for true zero,
which is represented by all zero bits)

On your PC (a LSB first machine) the bytes (NOT the fields) are in
reversed order. Also: IEEE includes a variety of NANs to represent
overflows, underflows and undefined values.

If you experiment, you should be able determine how many bits of exponent
and mantissa work. I seem to remember about 11 exponent bits, which
would give about 32-1-11 mantissa bits (+ the assumed leading 1 bit).
Mitchell R Grunes (grunes@imsy1.nrl.navy.mil)
Allied-Signal Technical Services
c/o Code 7230 Naval Research Lab

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[Message index]

		converting ieee-float-format to pw-wave-float-format By: SLAMECZKA on Fri, 26 August 1994 01:07
		Re: converting ieee-float-format to pw-wave-float-format By: grunes on Thu, 25 August 1994 12:39
		Re: converting ieee-float-format to pw-wave-float-format By: thompson on Fri, 26 August 1994 07:44
		Re: converting ieee-float-format to pw-wave-float-format By: caron on Thu, 25 August 1994 08:52
		Re: converting ieee-float-format to pw-wave-float-format By: grunes on Fri, 26 August 1994 06:51
		Re: converting ieee-float-format to pw-wave-float-format By: grunes on Fri, 26 August 1994 05:47

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