I found that the error occurs only if I take r = float. In the case if
r = int I can get an expression but I can't convert in using .n()
The term I get without .n() is
step4: definition of the velocity dispersion
100000
inf
/
[ 2
1.85669614564486E+10 I (((10628820000 x + 17218688400 x
]
/
1
+ 6973568802) log(100 x + 81) + 17218688400 x + 10460353203)
2 1062882 log(81) +
1594323
/(20000000000 x + 32400000000 x + 13122000000) -
-------------------------)
2000000
2 3
/(x (1.234567901234568 x + 1.0) ) dx
and with .n() I get the following error
Traceback (most recent call last):
File "friction.py", line 25, in <module>
print sig2(1).n()
File "/home/florian/sage/sage-3.4/local/lib/python2.5/site-packages/
sage/calculus/calculus.py", line 1512, in numerical_approx
approx = self._complex_mpfr_field_(ComplexField(prec))
File "/home/florian/sage/sage-3.4/local/lib/python2.5/site-packages/
sage/calculus/calculus.py", line 5710, in _complex_mpfr_field_
return self._convert(field)
File "/home/florian/sage/sage-3.4/local/lib/python2.5/site-packages/
sage/calculus/calculus.py", line 5637, in _convert
return typ(g)
File "/home/florian/sage/sage-3.4/local/lib/python2.5/site-packages/
sage/rings/complex_field.py", line 255, in __call__
return Parent.__call__(self, x)
File "parent.pyx", line 283, in
sage.structure.parent.Parent.__call__ (sage/structure/parent.c:3653)
File "coerce_maps.pyx", line 81, in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_ (sage/
structure/coerce_maps.c:2793)
File "coerce_maps.pyx", line 76, in
sage.structure.coerce_maps._call_ (sage/structure/coerce_maps.c:2700)
File "/home/florian/sage/sage-3.4/local/lib/python2.5/site-packages/
sage/rings/complex_field.py", line 279, in _element_constructor_
return x._complex_mpfr_field_( self )
File "/home/florian/sage/sage-3.4/local/lib/python2.5/site-packages/
sage/calculus/calculus.py", line 5710, in _complex_mpfr_field_
return self._convert(field)
File "/home/florian/sage/sage-3.4/local/lib/python2.5/site-packages/
sage/calculus/calculus.py", line 5631, in _convert
fops = [typ(op) for op in self._operands]
File "/home/florian/sage/sage-3.4/local/lib/python2.5/site-packages/
sage/rings/complex_field.py", line 255, in __call__
return Parent.__call__(self, x)
File "parent.pyx", line 283, in
sage.structure.parent.Parent.__call__ (sage/structure/parent.c:3653)
File "coerce_maps.pyx", line 81, in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_ (sage/
structure/coerce_maps.c:2793)
File "coerce_maps.pyx", line 76, in
sage.structure.coerce_maps._call_ (sage/structure/coerce_maps.c:2700)
File "/home/florian/sage/sage-3.4/local/lib/python2.5/site-packages/
sage/rings/complex_field.py", line 279, in _element_constructor_
return x._complex_mpfr_field_( self )
File "/home/florian/sage/sage-3.4/local/lib/python2.5/site-packages/
sage/calculus/calculus.py", line 1746, in _complex_mpfr_field_
raise TypeError
TypeError
But in principle I would like to use floats for r and therefore the
problem stated in my first thread is still valid
thank you very much for any advice
with best regards
florian
... who becomes more and more frustrated using sage...
p.s. I evaluated the integral using a for loop and this works very
well see below
def sig2(r):
grav_const = 4.3e-06
pi = 3.14159265358979323846
if r == 0:
return 0
max_int = 100
step = max_int/1000.;
sigma2 = 0.;
mass_r = mass(r);
volume_old = (4./3.)*pi*r**3;
sys.setrecursionlimit(100000)
print sys.getrecursionlimit()
for i in range(0,1000):
radius = r + i*step
volume_new = (4./3.)*pi*radius**3
mass_r = mass_r + (volume_new-volume_old)*rho(radius)
sigma2 = sigma2 + mass_r*rho(radius)/(radius**2)
volume_old = volume_new
return step*grav_const*sigma2/rho(r)
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