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MathGroup Archive 2000

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WorkingPrecision

  • To: mathgroup at smc.vnet.net
  • Subject: [mg23824] WorkingPrecision
  • From: bernd at bio.vu.nl (Bernd Brandt)
  • Date: Sat, 10 Jun 2000 03:00:40 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Dear members,

Is someone able to explain why Accuracy and Precision decrease when i increase WorkingPrecision ?

The following illustrates my question:

In: 
ni = NIntegrate[x Sqrt[x], {x, 0, 25}, AccuracyGoal -> 6, PrecisionGoal -> 6, 
WorkingPrecision -> 16, Compiled -> False]

In: Accuracy[ni]
	Precision[ni]

Out: 13
Out: 16

In:		ni - 1250
OUt:  -1.506340140622342*10^-6	
	
Doing the same with WorkingPrecision->32 will yield:
	 Accuracy[ni] returns  3 
	 Precision[ni] returns 7
And: ni-1250 now is less accurate: -0. 10^-4 

I am puzzled at this. Any help or a reference is highly appreciated.

Does someone have a good reference on Accuracy, Precision, AccuracyGoal, PrecisionGoal and WorkingPrecision?


Thank you,
Bernd Brandt


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