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Topic: standard floating point arithmetic in Mathematica?
Replies: 1   Last Post: Mar 28, 2014 3:31 AM

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Bob Hanlon

Posts: 906
Registered: 10/29/11
Re: standard floating point arithmetic in Mathematica?
Posted: Mar 28, 2014 3:31 AM
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It is not clear to me whether you want only results that are Real to be
displayed at that precision or all reals in an expression. Use one of the
following

$Post = If[Head[#]===Real,SetPrecision[#,17],#]&;

.1+.2

0.30000000000000004

1/3. E^(-Pi x)

0.333333 E^(-\[Pi] x)

%//N

0.333333 2.71828^(-3.14159 x)

$Post = (# /. x_Real:>SetPrecision[x,17])&;

.1+.2

0.30000000000000004

1/3. E^(-Pi x)

0.33333333333333331 E^(-\[Pi] x)

%//N

0.33333333333333331 2.7182818284590451^(-3.1415926535897931 x)


Bob Hanlon



On Thu, Mar 27, 2014 at 5:00 AM, Alan <alan.isaac@gmail.com> wrote:

> I would like to illustrate some limitations with floating point
> calculations. Can I force Mathematica to do floating point computations at
> a standard float size and the display the full results (as the same size
> float)?
>
> E.g., if I enter
> 0.1+0.2
> I would like to see
> 0.30000000000000004
>
> Thanks,
> Alan Isaac
>
>







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