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Re: Bugs with transcendental functions?
 To: mathgroup at christensen.cybernetics.net
 Subject: [mg1796] Re: Bugs with transcendental functions?
 From: wjrowe at ccgate.hac.com (Bill Rowe)
 Date: Mon, 31 Jul 1995 23:06:39 0400
 Organization: Hughes Space Company
In article <DC7E1v.1s9 at wri.com>, jin at eden.rutgers.edu (gum) wrote:
I have two similar equations listed below. The 1st one
came out OK, but the 2nd one didn't go anywhere.
The only difference is "p" in the 1st one is replaced
by "a" in the 2nd one.


I'm using mathematica 2.0 on NeXTStep 3.0. Is it a
bug of the version of MMA I have?



1. Input:=
 Solve[p (Log[x + a z]+ Log[ w + a z])/qq== y, x]


Output:=
 w + a z
{{x > (a z) + }}
 (qq y)/p
 E



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
 nonalgebraic 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.
In your first example none of the variables which appear as arguments to
the Log function appear outside of the Log function. Consequently, a
simple inversion of the Log function solves the equation.
In you second example, the symbol 'a' appears as an argument to the Log
function as well as elsewhere in the equation. I believe the Solve
function assumes the symbol 'a' could be a function of x, hence the
message.
Basically the behavior you describe is not a bug but a result of the
design of the Solve function.

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