Multiplication of power series looks tricky as for the term k of the resulting power series you need to access terms where sum index value to k. (ps1 next: i) and (ps2 next: k - i). Somehow the bloc of code defining the multiplicated serie needs to know about its current rank k.
You should not need a dedicated .* operator, you can handle it with only * operator with appropriate object testing. No real answer Le 30/05/2016 21:47, Erisa a écrit : > The fibonacciSequence example was really helpful. I made a new class > PowerSeries, a subclass of Generator. Then I defined a binary operation + > as follows: > > + aPowerSeries > ^ PowerSeries on: [ :ps | > | a b | > [ a := self next. > b := aPowerSeries next. > ps yield: (a + b) ] > repeat ] > > This works perfectly. But now I am struggling with how to define > multiplication. When I do PS1 * PS2, the first yield should be a := PS1 > next. b := PS2 next. ps yield (a * b). Thereafter would come the > PowerSeries, call it PSNew, (PS2 .* a) + (PS1 * PS2'), where .* is scalar > multiplication (easy to implement) and PS2' is the original PS2 (i.e., > rewound 1). I see several problems here. It looks like I need a way to > clone (fork?) a PowerSeries since in this computation I need both the > current PS2 and the original PS2 and be able to operate with them > independently. Second, how do I define the generator so that it first > yields the scalar (a*b) and thereafter is represented by the PowerSeries > PSNew? Finally, will the recursion in the definition of * blow up rapidly? -- Dr. Geo http://drgeo.eu
