i.e it's a Lua number -- a floating point. So a kind of conversion can happen between a floating point and a sp number (which has a limited range) Of course Lua has its routines, but probably they differs from TeX If I recall correctly, both use 32 bits, but if you extend to lets say 48 bit then the TeX routines are not good anymore.
Well, I'm not sure it's right, of course.
The lua numbers have enough precision to cast on the tex numbers (with rounding) but in practice I don't care too much. As we have standardized floats the behaviour is predictable. We could probably go completely float at the tex end but too many datastructures expect an integer so it's not worth the trouble. Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com | www.pragma-pod.nl -----------------------------------------------------------------