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Re: Puzzled by IntegerPart

  • To: mathgroup at smc.vnet.net
  • Subject: [mg114681] Re: Puzzled by IntegerPart
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Mon, 13 Dec 2010 03:50:17 -0500 (EST)


On 12 Dec 2010, at 11:40, Themis Matsoukas wrote:

> Round and Rational have solved the problem. But I am curious, why do the phantom decimals not show with N?
>
> N[100*1.15, 20]
>
> 115.
>
>
> Themis
>
This does not make sense (in Mathematica). 100*1.15 is a machine precision number:

In[55]:== Precision[100*1.15]

Out[55]== MachinePrecision

and applying N[?,20] to a MachinePrecision number does nothing at all. If you want a to convert it to a higher precision number as output you should use:

SetPrecision[100*1.15, 20]

 114.99999999999998579

If you only want to pad the output with zeros you can do:

NumberForm[100*1.15,{3,17}]
115.00000000000000000

All of this is actually fully documented.
Andrzej Kozlowski


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