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Input accuracy

• To: mathgroup at yoda.ncsa.uiuc.edu
• Subject: Input accuracy
• From: "Keith R. Slavin" <keith at videovax.tv.tek.com>
• Date: Wed, 07 Nov 90 12:45:18 PST

I have recently been trying to get mathematica to accept an input of GIVEN
accuracy, ie: Foo[1.3,25] implies 1.300000000000000000000000, ie: 25 digit
precision according to the Precision[] function, otherwise the
OUTPUT accuracy suffers due to the 'machine accuracy' assumed for '1.3'. The
only way I have found to do this is to use Rationalize[1.3,10^-25], and
use 13/10 in my calculations to arbitrary precision, but
Rationalize[] assumes an input of machine accuracy too, so

Rationalize[0.9999999999999999999,10^-25]

gives 1

which is not adequate for 25-digit processing!

Any ideas?

Thanks,

Keith Slavin,
Tektronix,
Beaverton,Or.
(503) 627-4907
keith at videovax.tv.tek.com