Well, if memory is really an issue, you can avoid the creation of the
intermediate tensor fields uR and dR by writing
gc = g.components()
igc = g.inverse().components()
Rc = R.components()
kr = 0
for a in M.irange():
for b in M.irange():
for c in M.irange():
for d in M.irange():
for i in M.irange():
for j in M.irange():
for k in M.irange():
for l in M.irange():
kr += gc[[a, i]]*igc[[b, j]]*igc[[c, k]]*igc
[[d, l]] \
*Rc[[i, b, c, d]]*Rc[[a, j, k, l]]
kr.expr()
It is certainly more efficient in term of memory, but less efficient in
term of CPU time, since the symmetries of the Riemann tensor are not taken
into account in the above writing.
Best wishes,
Eric.
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