Precision and CD's

J H Davenport J.H.Davenport at maths.bath.ac.uk
Tue Jul 20 22:53:55 CEST 1999


>>> Since it gets tiring to write (and read) numbers
>>> like 1.000000000000000000000 and 0.00000000000000000000
>>> you might prefer to say
>>> 1.0e0 precision 35.

Aha, so precision is purely for the benefit of humans (and possibly
some transmission economy, but if that interested us, we wouldn't be
using XML!).
> Let me repeat:  if the precision of a bigfloat in some representation
> is not apparent, then THAT IS NOT ACCEPTABLE.
But, as you say, it could always be made visible by printing enough zeros.

However, I could well see another constructor in bigfloat CD which had
a fourth child (probably the last one for compatibility). Note that
this constructor should generate exactly the same type of abstract
OpenMath object as the current one. Since most of the time
digits=precision, always making one side compute it, and the other
side verify it, seems redundant.

David - in this case, can you email me the currnet state of bigfloat
(I'm having troubles getting to the project web site) and I'll update
them.
>>> Mathematica has some crazy unenunciated rules that are something
>>> like the precision is the minimum of (the number of 
>>> input decimal digits*0.3010+some slush, 18)
Precisely why I was reluctant to even hint that implementers should go
down this road.
>>> James:  are we reconciled now?")
I hope so - what do you think?
James



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