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On the Function problem

  • To: mathgroup at yoda.ncsa.uiuc.edu
  • Subject: On the Function problem
  • From: "Roger B. Kirchner" <kirchner at cs.umn.edu>
  • Date: Wed, 10 Oct 90 11:50:19 CDT

Several people have pointed out that the problem with Function is a
bug in Derivative[1] which doesn't know how to handle Subtract in
the version of Function which uses variables.  The bug seems to be in
all current versions of Mathematica.

A couple of people have observed that the problem does not exist with
the version of Function which uses slots.  This is just as good for my
purposes because I want to deemphasize variable names in function definitions.

In[1]:= f = Function[x, x^2 - x]

                     2
Out[1]= Function[x, x  - x]

In[2]:= f'[x]

                      2
Out[2]= (Function[x, x  - x])'[x]

In[3]:= g = Function[#^2 - #]

          2
Out[3]= #1  - #1 & 

In[4]:= g'[x]

Out[4]= -1 + 2 x

Roger Kirchner
rkirchne at mathcs.carleton.edu


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