Hello,

## with sage manifold i tried the folowing commands (in a sage 9.1 notebook)

M = Manifold(4, 'M', structure='Lorentzian')

# -----------------------

Mani.<t,x,rh,ph> = M.chart(r"t X:(-oo,+oo) rh:(0,+oo):\rho ph:(0,2*pi):\phi")

# ---------------------

B = function('B')(X,rh,ph) d_Ph_X = function('d_Ph_X')(X,rh,ph) d_Ph_rh = function('d_Ph_rh')(X,rh,ph) d_Ph_ph = function('d_Ph_ph')(X,rh,ph)

# --------

g = M.metric()

g[0,0] = (-1+B**2* ((d_Ph_X/B**2)**2 +(d_Ph_rh/B**2)**2 +((1/rh d_Ph_ph/B**

*2)**2 )))

g[1,1] = B**2
g[2,2] = B**2
g[3,3] = rh**2*B**2

g[0,1] = B**2 (d_Ph_X/B**

*2) g[0,2] = B*

**2****( d_Ph_rh/B**2) g[0,3] = B

**2*( d_Ph_ph/B**2)

# -----------------

g.christoffel_symbols_display()

the line "g.christoffel_symbols_display()" makes the notebook overflow... i really don't understand why..

the computation even if it is rather tedious seems straightforward to me...

Any idea ? Any help would be greatly appreciated. Have a good day,