如下，已知列表vals，如何给出列表中任意一项对应的贝塞尔函数零点值所对应的贝塞尔函数的阶数?
比如vals[[7]]所对应函数式的第一个参数"3"如何给出?
{vals, funs} =
DEigensystem[{-Laplacian[u[x, y], {x, y}],
DirichletCondition[u[x, y] == 0, True]},
u[x, y], {x, y} \[Element] Disk[], 10]
vals
{BesselJZero[0, 1]^2, BesselJZero[1, 1]^2, BesselJZero[1, 1]^2,
BesselJZero[2, 1]^2, BesselJZero[2, 1]^2, BesselJZero[0, 2]^2,
BesselJZero[3, 1]^2, BesselJZero[3, 1]^2, BesselJZero[1, 2]^2,
BesselJZero[1, 2]^2}

#[[1,1]]&/@vals
如果形式不统一，用Cases更准些