polar_lift 'name' problem when integrating a multidimensional gaussian

[Lorenzo Monacelli]

Dear All,

I'm trying to integrate a multidimensional Gaussian with sympy. However, when I perform the integration, it crashes with an error related to polar_lift:

import sympy as sy

from sympy.abc import *

sy.init_printing()

C= sy.MatrixSymbol("C", 3, 3)

r = sy.IndexedBase("r", real = True)

a,b,c = sy.symbols("a,b,c", integer = True)

integ = sy.Integral( sy.exp(-r[a] * C[a,a] * r[a] - 2*r[a] * C[a,b] * r[b] - r[b]*C[b,b] * r[b]),

            (r[a], -sy.oo, sy.oo), (r[b], -sy.oo, sy.oo))

integ.doit()

In the last line, the code crashes with the following error

~/anaconda2/lib/python3.7/site-packages/sympy-1.6.dev0-py3.7.egg/sympy/matrices/expressions/matexpr.py in name(self)
    797     @property
    798     def name(self):
--> 799         return self.args[0].name
    800 
    801     def _eval_subs(self, old, new):

AttributeError: 'polar_lift' object has no attribute 'name'

If I replace the indexed variables with normal variables, the integration is performed (even if it is superslow, and if I ask for conds="none" it assumes it to diverge)

There is a way to perform integrals of multidimensional Gaussians? In principle, these kinds of integrals should be tabulated

Thanks for your attention,

Bests,

Lorenzo