MathGroup Archive 2014

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: standard floating point arithmetic in Mathematica?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg132486] Re: standard floating point arithmetic in Mathematica?
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Fri, 28 Mar 2014 03:31:50 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • Delivered-to: l-mathgroup@wolfram.com
  • Delivered-to: mathgroup-outx@smc.vnet.net
  • Delivered-to: mathgroup-newsendx@smc.vnet.net
  • References: <20140327090014.228D06A2F@smc.vnet.net>

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 at 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
>
>




  • Prev by Date: Re: standard floating point arithmetic in Mathematica?
  • Next by Date: Re: Combinatorica versus new graphs in V8
  • Previous by thread: standard floating point arithmetic in Mathematica?
  • Next by thread: Re: standard floating point arithmetic in Mathematica?