id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
9130,Access to beta function,kcrisman,burcin,"Although Maxima has the beta function, Sage doesn't:
{{{
sage: a, b, c = var('a b c')
sage: assume(a > 0)
sage: assume(b > 0)
sage: x = var('x')
sage: beta_dist = x**(a-1) * (1 - x)**(b-1)
sage: c = integral(beta_dist, x, 0, 1)
sage: c
beta(a, b)
sage: c(a=.5,b=.5)
beta(0.500000000000000, 0.500000000000000)
sage: c(a=.5,b=.5).n()
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
/Users/karl-dietercrisman/ in ()
/Users/karl-dietercrisman/Desktop/sage-4.4.2/local/lib/python2.6/site-packages/sage/symbolic/expression.so in sage.symbolic.expression.Expression.n (sage/symbolic/expression.cpp:17042)()
TypeError: cannot evaluate symbolic expression numerically
}}}
This *is* is Ginac, though, and there is even room for defining it in symbolic/expression.pyx . It probably is also included in some of our other libraries, as a standard special function.
----
Apply
* [attachment:trac_9130_beta_function.patch]
* [attachment:trac_9130-py_float_segfault.patch]
* [attachment:trac_9130_beta_function.2.patch]
* [attachment:trac_9130_beta_function.3.patch]",enhancement,needs_review,major,sage-4.7.1,symbolics,,"special function, pynac, sd35.5",benjaminfjones,,"Karen T. Kohl, Burcin Erocal",,N/A,,,,,