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reduced functionality of Solve
*To*: mathgroup at smc.vnet.net
*Subject*: [mg44222] reduced functionality of Solve
*From*: Andrew Collier <colliera at nu.ac.za>
*Date*: Wed, 29 Oct 2003 03:34:05 -0500 (EST)
*Sender*: owner-wri-mathgroup at wolfram.com
hello,
this may be a naive idea but i expected the functionality of software to
improve with later releases. this, in my opinion, does not seem to be the
case from mathematica 4.1 to 5.0... or maybe i am just missing something.
in a script i have the following bit of code:
-------------------------------------------------------------------------
F[W_, y_] := Exp[-W(Cos[y]^2/Tp + Sin[y]^2/Tn)]
Tn = 3000;
Tp = 2000;
Solve[{D[F[W, y], y] Tan[y] == 2 F[W, y], W == 1000 Sec[y] ^ 2}, {W, y}];
N[%] // TableForm
-------------------------------------------------------------------------
now, with mathematica 4.1 this gives:
-------------------------------------------------------------------------
InverseFunction::ifun:
Inverse functions are being used. Values may be lost for multivalued
inverses.
Solve::ifun: Inverse functions are being used by Solve, so some solutions may
not be found.
In[5]:=
Out[5]//TableForm= W -> 7000. y -> -1.95839
W -> 7000. y -> 1.95839
W -> 7000. y -> -1.1832
W -> 7000. y -> 1.1832
-------------------------------------------------------------------------
which is useful and the kind of result i am after. however, after
upgrading to mathematica 5.0 the same bit of code gives:
-------------------------------------------------------------------------
Solve::tdep: The equations appear to involve the variables to be solved for in
an essentially non-algebraic way.
In[5]:=
-------------------------------------------------------------------------
now i read in the manual that Solve "deals primarily with linear and
polynomial equations", but i would expect that if i got a useful answer
with 4.1 i should get the same (or better!) with 5.0.
is there some way of getting the old behaviour with the newer version of
mathematica?
many thanks and best regards,
andrew collier.
--
Andrew B. Collier
Antarctic Research Fellow tel: +27 31 2601157
Space Physics Research Institute fax: +27 31 2616550
University of Natal, Durban, 4041, South Africa
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