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MathGroup Archive 1995

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Re: Bugs with transcendental functions?

  • To: mathgroup at christensen.cybernetics.net
  • Subject: [mg1813] Re: Bugs with transcendental functions?
  • From: fateman at peoplesparc.cs.berkeley.edu (Richard J Fateman)
  • Date: Mon, 31 Jul 1995 23:09:40 -0400
  • Organization: University of California, Berkeley

In article <DCBwtr.4z1 at wri.com>, Bill Rowe <wjrowe at ccgate.HAC.COM> wrote:
...
>|2. Input:=
>|           Solve[a (-Log[x + a z]+ Log[ w + a z])/qq== y, x]


>|Solve::tdep: 
>|   The equations appear to involve transcendental
>|     functions of the variables in an essentially
>|     non-algebraic way.

>|Output:=
>|      a (Log[w + a z] - Log[x + a z])
>|Solve[------------------------------- == y, x]
>|                    qq

>I am sure it is not a bug related to your version of MMA since I get the
>same result using MMA version 2.2.1 on a Macintosh.

.....

>Basically the behavior you describe is not a bug but a result of the
>design of the Solve function.



No, its a bug. Here's a newer version of Mathematica. (version 2.2 on
HP 9000).


In[1]:=   Solve[a (-Log[x + a z]+ Log[ w + a z])/qq== y, x]

                (-(qq y) + a Log[w + a z])/a
Out[1]= {{x -> E                             - a z}}

This bug was fixed some time ago, I thought. It would, in any case,
be a strange interpretation of symbolic constants like a or qq
 to think that they may all depend on the unknown(s) you are solving
for (here, x).  You could hardly solve any equation under those
assumptions. 
RJF
-- 
Richard J. Fateman
fateman at cs.berkeley.edu   510 642-1879


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