]> On Sat, 2003-12-06 at 14:18, Brian Hurt wrote: > 30 decimal digits is enough accuracy to measure the > distance between here and the Andromeda Galaxy in microns. Why does he > need such a ridiculous amount of precision? Standard eigen problem sometimes needs ridiculous precision: the scalar product of two vectors: sigma (i=1,n) (v1_i * v2_i) sometimes involves cancellation of large values. To see why there is a problem here, consider: 1.000001e20 - 1e20 - (1.000001e-20 - 1e-20) and you can see you need around 50 digits precision, just to get an answer with 1 digit of precision. The eigen problem with large numbers of dimensions arises in, for example, quantum chemistry. ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners