On 12/23/10 2:19 AM, KvS wrote:
On Dec 23, 6:42 pm, Jason Grout<jason-s...@creativetrax.com> wrote:
On 12/23/10 1:02 AM, KvS wrote:
In addition to the previous post, if I change the contents of the
first cell to
f=BetaLP1.getkthMomentAt(1,1)
g=symbolic_expression(str(f(x))).function(x)
print g(0)
it does yield 1 as well. Any hints?
Can you post the code for BetaLP1.getkthMomentAt(1,1) so we can try it?
Thanks,
Jason
plus: thanks in advance, of course!
Yes, something does seem weird. When I modify your getkthMomentAt
function to:
def getkthMomentAt(self,k,t):
charFunc=self.getCharacteristicExponent()
i=sqrt(-1)
f=(exp(-t*charFunc(-i*x))).function(x)
for _ in range(k):
f=f.derivative()
return f
then I get the following odd sequence of results:
sage: mygammaexpr=f.operands()[0].operands()[0].operands()[1].operands()[0]
sage: mygammaexpr
gamma(-x - 1/2)
sage: mygammaexpr(x=0)
Traceback (most recent call last):
...
ValueError: argument must be >= -1
sage: mygammaexpr
gamma(-x - 1/2)
sage: gamma(-x-1/2) - mygammaexpr
0
sage: mygammaexpr(x=0)
-2*sqrt(pi)
Definitely weird. Apparently subtracting mygammaexpr from gamma(-x-1/2)
makes mygammaexpr suddenly realize that it's okay to evaluate it at x=0.
Jason
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