Re: Why Mathematica does not issue a warning when the calculations
- To: mathgroup at smc.vnet.net
- Subject: [mg117786] Re: Why Mathematica does not issue a warning when the calculations
- From: Daniel Lichtblau <danl at wolfram.com>
- Date: Thu, 31 Mar 2011 04:03:13 -0500 (EST)
Richard Fateman wrote:
> On 3/29/2011 4:53 AM, Andrzej Kozlowski wrote:
>> In addition (for some curious reason) Richard never bothers to point out that
>>
>> z = 1.0000000000000000000;
>> Block[{$MaxPrecision = 20, $MinPrecision = 20},
>> Table[(z = 2*z - z), {42}]]
>>
>> will give the output that other systems give (with all the accompanying problems your post below mentions).
>>
>> In other words, his (and only his) gripe is only with Mathematica's *default* arithmetic.
>
> I have other gripes, too :)
>
> It would be nicer if one could simple do this
>
> $DefaultArithmetic = Precision[20] and try some computation, vs.
> $DefaultArithmetic = Significance
>
> RJF
Could do
$MinPrecision = 20;
$MaxPrecision = 20;
Not the most intuitive way to go about things. But it should have the
desired effect of a putative $DefaultArithmetic = Precision[20]
Daniel Lichtblau
Wolfram Research