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From: Mirsad Todorovac
Subject: Real with attributes (...)
Date: 1 Jul 2003, 15:36:03

Please read without prejudice!

What would you think of the following: we all know about various bitsizes
Integer and Cardinal types.

What I've seen was a "customized" real type.  Imagine you have to store
lots of data for GSM-encoding, or some similar measurement purpose. Lots
of bits are wasted, as they don't correspond to accurate digits of
measurement. I.e. on a weather station that has only an occassional link
to a satellite.

For example, let's suppose we have lots of data that that we could express
as reals in 16-bit precision, and all fit between -0.5 and 0.5 (for
example, but standard can be defined in different way):

type MyReal = Real attribute (Exponent = 0, Mantissa = 16);

     GSMReal = Real attribute (Exponent = 8, Mantissa = 8);

The latter could represent a number with same range like IEEE single
precision float, just with only 2 accurate digits.

     or even

     TEMPReal = Real attribute (ExponentRange = 0..15, Mantisa = 4);

for keeping the temperature in one byte from range of 0.0625 K to 30720 K
(where precision is not that much important as the value on the
logarithmic scale ...)

The compiler could use hardware floating point when it's faster than
emulation with less bits of precision, then round/truncate when storing
back into memory/variable.

This is just a tip, not a real syntax or semantics proposal.

Mirsad

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