On Tue, 03 Feb 2009 21:25:21 +0300, Sean Kelly <[email protected]> wrote:
Andrei Alexandrescu wrote:
Ary Borenszweig wrote:
Andrei Alexandrescu escribió:
I've updated my code and documentation to include series (as in math)
in the form of infinite ranges. Also series in closed form (given n
can compute the nth value without iterating) are supported as
random-access ranges.
Also Stride is provided. The Matrix container (speaking of scientific
computing with D!) will support various representational choices,
most importantly the ones endorsed by high-performance libraries. For
Matrix, Stride is an important component as I'm sure anyone who's
ever written a matrix knows.
http://ssli.ee.washington.edu/~aalexand/d/web/phobos/std_range.html
http://ssli.ee.washington.edu/~aalexand/d/web/phobos/std_algorithm.html
Back to series. Finally my dream has come true: I can define a decent
Fibonacci series clearly and efficiently in one line of code. No more
idiotic recursive function that takes exponential time to finish!
auto fib = series!("a[n-1] + a[n]")(1, 1);
// write 10 Fibonacci numbers
foreach (e; take(10, fib)) writeln(e);
That is *SO* awesome!!
Thanks! Constant-space factorial is just a line away:
auto fact = series!("a[n] * (n + 1)")(1);
foreach (e; take(10, fact)) writeln(e);
Awesome :-) I think that proves the efficacy of the approach all by
itself.
Sean
I wonder how efficent it is? Does it store last few sequence elements or
re-compute then again and again?
I wouldn't use it in the latter case.
