On 5 September 2012 09:34, Cindy <[email protected]> wrote: > Hi, David, > > Could you please explain a little bit about the code?
Sure, but you should make a little effort to play with it yourself for a bit first. > For the example you use, it seems I is an ideal above 17, what does [0] > mean? The command K.primes_above(...) returns a list of the prime ideals above the given rational prime. The [0] selects the first (zeroth?) from the list. So yes, I is an ideal above 17 which I am just using as an example (any number field ideal, except the zero ideal, would work here). There are lots of examples like this in the Sage documentation. > In the end do we get a basis of the dual of I? Yes, that's the whole point of the exercise :-). Did you read the documentation for "trace_dual_basis"? You should know that you can get documentation on any method of any Sage object by typing its name then ?, e.g. sage: K.trace_dual_basis? will tell you lots more about this method. > Why do we need to put > I.basis() in the bracket of trace_dual_basis? Because trace_dual_basis takes a list of generators as its argument -- it can calculate the trace dual of any Z-submodule of K, it needn't be an ideal. Regards, David -- You received this message because you are subscribed to the Google Groups "sage-support" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-support?hl=en.
