Comment #14 on issue 895 by [email protected]: series method does not work
if the point is not 0
http://code.google.com/p/sympy/issues/detail?id=895
OK, this work was disallowing evaluation at x0 = 0. My work has been
focussed on getting it to be right. If my work is reviewed and accepted,
this issue can be closed.
He notes:
In [9]: exp(1+x).series(x,point=0).subs(x,x-1)
Out[9]: O(1)
The problem here seems to be the O(x**6) symbol. Since,
O(f(x)) represents O(f(x)) at the point x = 0, the substitution
fails.
Yes...that's the problem. The new issue that should be opened is
1) implement O() at x0!=0
2) implement multivariate expansion as noted above
btw, here are the expression that he gave above in pull/61
h[2] >>> (x**4).series(x,0,2)
x**4
h[3] >>> (x**4).series(x,1,2)
-3 + 4*x + 6*(1 - x)**2 - 4*(1 - x)**3 + (1 - x)**4
h[4] >>> (2**x).series(x,0,3)
1 + x*log(2) + x**2*log(2)**2/2 + O(x**3)
h[5] >>> (2**x).series(x,1,3)
2 - 2*(1 - x)*log(2) + (1 - x)**2*log(2)**2
h[6] >>> (x**x).series(x,0,3)
1 + x*log(x) + x**2*log(x)**2/2 + O(x**3*log(x)**3)
h[7] >>> (x**x).series(x,1,3)
x + (1 - x)**2
h[8] >>> ((1+x)**x).series(x,0,3)
1 + x**2 - x**3/2 + O(x**4)
h[9] >>> ((1+x)**x).series(x,1,3)
1 + x + (1 - x)**2*log(2) - 2*(1 - x)*log(2) + (1 - x)**2 + (1 -
x)**2*log(2)**2
Note that sympy no longer returns O() if you aren't evaluating at x0=0
--
You received this message because you are subscribed to the Google Groups
"sympy-issues" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sympy-issues?hl=en.
