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Re: Rounding to a certain number of decimal places

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  Re: Rounding to a certain number of decimal places Heike Gramberg <heike.gramberg@gmail.com> - 2011-05-28 11:18 +0000

#2755 — Re: Rounding to a certain number of decimal places

You can use NumberForm for this. Try something like

NumberForm[a, {Infinity,n}]

This should print a with n digits to the right of the decimal point (adding
zeros when needed).

Heike.

On 27 May 2011, at 11:14, Andrew DeYoung wrote:

> Hi,
> 
> I would like to be able to round a number to a certain, specified
> number of decimal places (not number of digits), including zeros.
> Suppose that some function f does this, and takes two arguments, the
> number to be rounded and the number of decimal places to which to
> round:  f[number, numPlaces].  Then, for example, I would like the
> following results, if possible:
> 
> f[0.8168, 3] = 0.817
> f[1.8168, 3] = 1.817
> f[10.8168, 3] = 10.817
> f[100.8168, 3] = 100.817
> f[0.99, 3] = 0.990
> f[0.9, 3] = 0.900
> f[0.00572, 3] = 0.006
> 
> Is there a function f (either built-in or a custom function) that can
> do this?  Mathmatica's built-in function NumberForm does not quite do
> this because the user specifies the number of digits, not the number
> of decimal places.  Also, NumberForm does not count zeros after the
> decimal point as digits, nor does it add extra zeros as needed if they
> are redundant.
> 
> Am I getting into deep water here, or is there something
> straightforward that can do what I would like?
> 
> I am running Mathmatica 7.  Also, I do not need to be able to do
> further computations on the output; I will be converting the output to
> a string, anyway.
> 
> Thank you very much for your time.
> 
> Andrew DeYoung
> Carnegie Mellon University
> 

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