Talk:Formal power series

Is it possible for non-functional language?

As alway, I misunderstood the task, the sin & cos is not defined by Integral of each other, but by explicit series definition.
I just wondered if non-functional language can accomplish the task. Is my examples totally go the wrong way, or 1 step away from goal? -- badmadevil 02:49, 6 April 2008 (MDT)

You beat to me flagging it as incorrect :-) And the key is lazyness, which in principle should also work in a non-functional language. As D doesn't seem to support it directly, you'll have to emulate it: Each coefficient should be a class that either already has a concrete value (an infinite precision rational, if available), or contains a call to a generator that can calculate the value. The first time the value is required, the generator is called, the next time, the cached value is used ("call-by-need"). That will also get rid of the inefficiencies in your implementation when do e.g. multiply several series (which causes the same coefficients to be calculated many times). And you need an infinite list of coefficients, which can be done with the same trick for a cons-cell. Yes, it's much nicer if the language does this naturally, which is the point of this task :-) --Dirkt 03:09, 6 April 2008 (MDT)