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Re: InverseFunction returning working function or just a symbol

  • To: mathgroup at
  • Subject: [mg126574] Re: InverseFunction returning working function or just a symbol
  • From: Murray Eisenberg <murray at>
  • Date: Sat, 19 May 2012 05:49:22 -0400 (EDT)
  • Delivered-to:

Please don't include all the In[...] and Out[...] labels, because they
make it hard to copy and paste executable code into Mathematica.

On 5/18/12 5:23 AM, L=E1szl=F3 S=E1ndor wrote:
> Hi all,
> I am puzzled by the following behavior (focus on the end, the rest is only to provide context):
> In[88]:== u[c_,l_]:==Log[c]-Log[1+l^(1+k)/(1+k)]
> In[14]:== T[z_]:==(1-0.84/1.3) * z
> In[103]:== umaxType[n_]:==MaxValue[{u[n l-T[n l],l],l>==0},l]
> In[101]:== lType[n_]:==ArgMax[{u[n l-T[n l],l],l>==0},l]
> In[105]:== zType[n_] :== n lType[n]
> In[111]:== Type :== InverseFunction[zType]
> In[134]:== Type[5345]
> Out[134]== 5030.99
> In[136]:== Type[2]
> Out[136]== (zType^(-1))[2]
> In[137]:== Type[4324424]
> Out[137]== (zType^(-1))[4324424]
> I understand that there could be many justified reasons why the inversion might not work for a specific argument. Still, I am deeply puzzled that so metimes I receive back a symbol that nothing else is able to do anything about (why not an error message, then?), sometimes a number. How could this be improved?
> Thanks!

Murray Eisenberg                     murray at
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305

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