MathGroup Archive 1997

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

Search the Archive

Re: Expanding function names to explicit formulas

  • To: mathgroup at smc.vnet.net
  • Subject: [mg8164] Re: [mg8104] Expanding function names to explicit formulas
  • From: David Withoff <withoff>
  • Date: Sat, 16 Aug 1997 11:51:07 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

> Hello,
> 
> Is there any way to convert input or output that includes function
> names (say, Erf[x]) to its explicit mathematical form (with the integral 
> symbol and such)?
>  
> Regards.
> -- 
>   __|__
> ___\_/___   Paulo Mouat,
>    ___      mouat at mail.telepac.pt
>   |___|     http://www.geocities.com/Vienna/8804/
>   |___|

You can do this in the same way that you can convert an output such
as the integer 4 into its explicit mathematical form 2+2:

In[5]:= 4 /. 4 -> HoldForm[2+2]

Out[5]= 2 + 2

If you release the hold, then Mathematica will convert 2+2 into 4, and
will likewise convert the integral represention of Erf[x] into Erf[x].

In[14]:= convert[p_] := p /. Erf[x_] ->     
                    HoldForm[2/Sqrt[Pi] Integrate[Exp[-t^2], {t, 0, x}]]

In[15]:= result = convert[Erf[x]]

                           2
         2 Integrate[Exp[-t ], {t, 0, x}]
Out[15]= --------------------------------
                     Sqrt[Pi]

In[16]:= ReleaseHold[result]

Out[16]= Erf[x]

Dave Withoff
Wolfram Research


  • Prev by Date: Forcing 'Plus' to format nicely
  • Next by Date: More questions on expanding function names to explicit forms
  • Previous by thread: Expanding function names to explicit formulas
  • Next by thread: Mathematica Art