Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2013

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

Search the Archive

Re: Function with optional default argument cannot cache

  • To: mathgroup at smc.vnet.net
  • Subject: [mg130678] Re: Function with optional default argument cannot cache
  • From: Waclaw Kusnierczyk <waku at idi.ntnu.no>
  • Date: Wed, 1 May 2013 21:40:10 -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: <20130501073754.8ADA36A27@smc.vnet.net>

Interesting.  Looks like you'd need to cover the default value case 
manually:

    f[x_, y_] := f[x, y] = {Pause[1], x, y}
    f[x_] := f[x, 2]

But arguably it should not be necessary.

vQ

On 05/01/2013 09:37 AM, Dan O'Brien wrote:
> Is there a discussion somewhere on why this is?
>
> In[1]:= $Version
> f[x_, y_: 2] := f[x, y] = {Pause[1], x, y}
> f[1, 2] // AbsoluteTiming
> f[1, 2] // AbsoluteTiming
> f[1] // AbsoluteTiming
> f[1] // AbsoluteTiming
>
> Out[1]= "9.0 for Microsoft Windows (64-bit) (January 25, 2013)"
>
> Out[3]= {1.014002, {Null, 1, 2}}
>
> Out[4]= {0., {Null, 1, 2}}
>
> Out[5]= {1.029602, {Null, 1, 2}}
>
> Out[6]= {1.014002, {Null, 1, 2}}
>




  • Prev by Date: Help with RootLocusPlot
  • Next by Date: Re: Plot with axes exchanged
  • Previous by thread: Function with optional default argument cannot cache results
  • Next by thread: Re: Function with optional default argument cannot cache results