Ndim_ := 4:
x1_ := t:
x2_ := r:
x3_ := theta:
x4_ := phi:
complex_ := {}:
eta11_ := 1:
eta22_ := -1:
eta33_ := -1:
eta44_ := -1:
bd11_ := exp(1/2*nu(r)):
bd22_ := exp(1/2*lambda(r)):
bd33_ := r:
bd44_ := r*sin(theta):