pi and e not evaluated when i use my own classes

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This question might be related to this question: http://ask.sagemath.org/question/966/problem-with-sign-sgn-and-n

I have a symbolic calculation and I do evaluate it numerically. Within one of my classes (within my notebook; no external files) I evaluate this term

-1/e^(1/10*abs(-0.0555555555556*pi - 26714619/51021164)) + 1

within a for loop.

I am getting the following error:

File "", line 1, in <module> File "/tmp/tmpkItECC/___code___.py", line 113, in <module> __temp=MuObject.calcValue((mu_enlacement[i])(**param_dict)) File "/tmp/tmpJuxeqk/___code___.py", line 97, in calcValue self._result[self._k,_sage_const_0 ]=R(self._value(theta_1=item[_sage_const_0 ],mu_t=item[_sage_const_1 ],mu_j=item[_sage_const_1 ])) File "parent.pyx", line 988, in sage.structure.parent.Parent.__call__ (sage/structure/parent.c:7326) File "coerce_maps.pyx", line 156, in sage.structure.coerce_maps.NamedConvertMap._call_ (sage/structure/coerce_maps.c:4235)
File "expression.pyx", line 862, in sage.symbolic.expression.Expression._mpfr_ (sage/symbolic/expression.cpp:5117)
File "expression.pyx", line 796, in sage.symbolic.expression.Expression._eval_self (sage/symbolic/expression.cpp:4912) TypeError: Cannot evaluate symbolic expression to a numeric value.

If I copy paste the expression

print
(-1/e^(1/10*abs(-0.0555555555556*pi - 26714619/51021164)) + 1).n()

to my notebook it evaluates fine to:

0.0674319647572598

I even tried to replace pi and e using a dictionary but I can't get it working.

Any ideas what i am doing wrong?

Thanks in advance,

Markus P.S.: I can make the notebook public if usefull

Accepted Answer

I don't know why this is happening, but here are some workarounds: one option is to replace

self._value(theta_1=item[0],mu_t=item[1],mu_j=item[1])

by

self._value(theta_1=item[0],mu_t=item[1],mu_j=item[1], e=e, pi=pi)

A second option: right after the line

self._value=self._value(**self.th1_dict)(**self.pre10_dict)(**self.constants).trig_reduce().simplify() #set dictionary values

add the line

self._value = self._value(**self.constants)

By the way, you can also replace the "constants" dictionary with

    self.constants={
        "pi": pi,
        "e": e
        }

to give better precision.

Thanks a million time for this indeed helpfull answer. BTW: that behaviour seems like a bug to me. After adding e=e... in the first of the if loops all the others also work fine. Looks like sage forgets about the constants. Should I try to file a bug here?
Louis Cypher (Jan 01 '12)
File a bug if you can come up with a small example which displays the behavior. Your current worksheet is too complicated to figure out exactly where the bug lies.
John Palmieri (Jan 02 '12)

pi and e not evaluated when i use my own classes

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