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WorkingPrecision and plotting functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg84236] WorkingPrecision and plotting functions
  • From: Szabolcs Horvát <szhorvat at gmail.com>
  • Date: Fri, 14 Dec 2007 23:16:23 -0500 (EST)

In Mathematica 6, the WorkingPrecision option can be passed to plotting 
functions.  But it seems that even when this option is used, these 
functions do substitute at least one machine precision number into the 
expression passed to them.

Shouldn't machine precision numbers be avoided completely when a high 
WorkingPrecision is specified (to prevent warning messages from 
functions like FindRoot which require a high WorkingPrecision for some 
computations)?

This is the code I used to test this:

f[x_?NumericQ] := (Print[Precision[x], " ", x]; Sin[x])

Plot[f[x], {x, 0, 1}, WorkingPrecision -> 50]

MachinePrecision 0.0000204286
50. 2.0408163265306120039922814718771904018979057582328*10^-8
50. 0.019628661201530398644488073500724567566066980361938
50. 0.040908357085458646462683418576489202678203582763672
...
...


Szabolcs


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