Hi,
I am trying to solve the following equation:
sage: f(x)=((1-0.15)/(1-0.15+(0.15/(1-x*0.15)^22)))^3-x
sage: solve(f,x)

This gives me the following error, which doesn't make much sense to me.

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call  
last)

/Users/geg/<ipython console> in <module>()

/Applications/sage/local/lib/python2.6/site-packages/sage/symbolic/ 
relation.pyc in solve(f, *args, **kwds)
     478     """
     479     try:
--> 480         return f.solve(*args,**kwds)
     481     except AttributeError:
     482         from sage.symbolic.ring import is_SymbolicVariable

/Applications/sage/local/lib/python2.6/site-packages/sage/symbolic/ 
expression.so in sage.symbolic.expression.Expression.solve (sage/ 
symbolic/expression.cpp:22150)()

/Applications/sage/local/lib/python2.6/site-packages/sage/interfaces/ 
expect.pyc in __call__(self, *args, **kwds)
    1380
    1381     def __call__(self, *args, **kwds):
-> 1382         return self._obj.parent().function_call(self._name,  
[self._obj] + list(args), kwds)
    1383
    1384     def help(self):

/Applications/sage/local/lib/python2.6/site-packages/sage/interfaces/ 
expect.pyc in function_call(self, function, args, kwds)
    1288                                        [s.name() for s in  
args],
    1289                                        ['%s=%s'% 
(key,value.name()) for key, value in kwds.items()])
-> 1290         return self.new(s)
    1291
    1292     def _function_call_string(self, function, args, kwds):

/Applications/sage/local/lib/python2.6/site-packages/sage/interfaces/ 
expect.pyc in new(self, code)
    1084
    1085     def new(self, code):
-> 1086         return self(code)
    1087
    1088      
###################################################################

/Applications/sage/local/lib/python2.6/site-packages/sage/interfaces/ 
expect.pyc in __call__(self, x, name)
    1019
    1020         if isinstance(x, basestring):
-> 1021             return cls(self, x, name=name)
    1022         try:
    1023             return self._coerce_from_special_method(x)

/Applications/sage/local/lib/python2.6/site-packages/sage/interfaces/ 
expect.pyc in __init__(self, parent, value, is_name, name)
    1423             except (TypeError, KeyboardInterrupt,  
RuntimeError, ValueError), x:
    1424                 self._session_number = -1
-> 1425                 raise TypeError, x
    1426         self._session_number = parent._session_number
    1427

TypeError: Error executing code in Maxima
CODE:
        sage14 : to_poly_solve(sage10,sage13)$
Maxima ERROR:
        Assuming that  
2.572052771128644e 
-55 
*x 
^ 
66 
-1.131703219296603e 
-52 
*x 
^ 
65 
+ 
2.452023641809308e 
-50 
*x 
^ 
64 
-3.487322512795459e 
-48 
*x 
^ 
63 
+ 
3.661688638435233e 
-46 
*x 
^ 
62 
-3.02699594110646e 
-44 
*x 
^ 
61 
+ 
2.05163058230549e 
-42 
*x 
^ 
60 
-1.172360332745994e 
-40 
*x 
^ 
59 
+ 
5.764104969334469e 
-39 
*x 
^ 
58 
-2.476430283121475e 
-37 
*x 
^ 
57 
+ 
9.410435075861606e 
-36 
*x 
^ 
56 
-3.193844631807575e 
-34 
*x 
^ 
55 
+ 
9.758969708300927e 
-33 
*x 
^ 
54 
-2.702483919221794e 
-31 
*x 
^ 
53 
+ 
6.820554653274052e 
-30 
*x 
^ 
52 
-1.576305964312226e 
-28 
*x 
^ 
51 
+ 
3.34965017416348e 
-27 
*x 
^ 
50 
-6.567941517967608e 
-26 
*x 
^ 
49 
+ 
1.191959756964492e 
-24 
*x 
^ 
48 
-2.007511169624407e 
-23 
*x 
^ 
47 
+ 
3.145100832411571e 
-22 
*x 
^ 
46 
-4.592845660029597e 
-21 
*x 
^ 
45 
+ 
6.262971354585815e 
-20 
*x 
^ 
44 
-7.987557669616691e 
-19 
*x 
^ 
43 
+ 
9.540693883153281e 
-18 
*x 
^ 
42 
-1.068557714913174e 
-16 
*x 
^ 
41 
+ 
1.123355546447224e 
-15 
*x 
^ 
40 
-1.10948695945426e 
-14 
*x 
^ 
39 
+ 
1.030237890922699e 
-13 
*x 
^ 
38 
-8.999779277056846e 
-13 
*x 
^ 
37 
+ 
7.399818516783484e 
-12 
*x 
^ 
36 
-5.72889175516733e 
-11 
*x 
^ 
35 
+ 
4.177316905347902e 
-10 
*x 
^ 
34 
-2.8692681784864726e 
-9 
*x 
^ 
33 
+ 
1.8565852938761138e 
-8 
*x 
^ 
32 
-1.1316329440808763e 
-7 
*x 
^ 
31 
+ 
6.496411389445956e 
-7 
*x 
^ 
30 
-3.5115737808419006e 
-6 
*x 
^ 
29 
+ 
1.786590236047529e 
-5*x^28-8.551201844988561e-5*x^27+3.848041527553564e-4*x^26-. 
001626814924957227*x^25+.006455619830316614*x^24-. 
02402094856854791*x^23+.08370962213783728*x^22-.2728329566931009*x^21+. 
8303702781628282 
*x 
^ 
20 
-2.355707893620063 
*x 
^ 
19 
+ 
6.216678118439924 
*x 
^ 
18 
-15.22550497577382 
*x 
^ 
17 
+ 
34.51506024624435 
*x 
^ 
16 
-72.20248123719546 
*x 
^ 
15 
+ 
138.897086824694 
*x 
^ 
14 
-244.7350019836468 
*x 
^ 
13 
+ 
393.1470391342294 
*x 
^ 
12 
-572.7129912818109 
*x 
^ 
11 
+ 
751.8090164270538 
*x 
^ 
10 
-882.7296150886173 
*x 
^ 
9 
+ 
918.7738209313588 
*x 
^ 
8 
-838.4801227519146 
*x 
^ 
7 
+ 
661.7724868308338 
*x 
^ 
6 
-443.7020662052342 
*x^5+246.62875545*x^4-109.676271375*x^3+36.8577*x^2-8.415*x+1.0 # 0
`allroots': not a polynomial:
errexp1
#0: to_poly_solve(e=.6141249999999999/(0.15/(1-0.15*x)^22+0.85)^3-x =  
0,vars=x)(topoly_solver.mac line 15)

I can solve this equation using Mathematica, but would prefer to use  
sage. Any ideas ?

regards,
Geir Egeland
phone +47 906 40 507
email: geir.egel...@gmail.com
PhD Candidate
University of Stavanger





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