Talk:Sum of squares

Is this too similar to Sum and product of array? --Mwn3d 22:42, 27 January 2008 (MST)

I think not. The sum-and-product task lets us see how these functions are specified, but they don't let us see them in relationship with another function. The point of sum-fo-squares, it seems to me, is to let us see how basic function composition occurs. It takes more than one function to show that. --TBH 10:01, 28 January 2008 (MST)

If that is the goal, perhaps a function composition task would be appropriate. --IanOsgood 10:07, 28 January 2008 (MST)

I don't think this counts as function composition. This is just accumulation, which is why I think it's similar to the sum and product. The capital sigma and capital pi symbols in math aren't really functions, and this task would use a capital sigma in its definition. --Mwn3d 10:39, 28 January 2008 (MST)

If summation-of-series and product-of-series are not going to be considered functions within this site, what should they be called instead? They easily fall within a common meaning of the word. To see how, I recommend that we take the Wikipedia page on function composition as a starting point. --TBH 11:32, 28 January 2008 (MST)

Function composition may be too broad a topic for a single task. Consider the following:

g (f y)
g (x f y)
(f x) g (f y)
fi (g (f y))
fi ((f x) g (f y))
y g (f y)
x g (f y)
(f y) g (h y)
(x f y) g (x h y)

In the notation used above f, g, and h are functions, fi is the function inverse to f, and data arguments are indicated as x and y.

These nine compostional structures are primary forms in the J programming language, so from the perspective of demonstrating J code nothing less than this set seems adequate. My intuition is that this set is too large to be demonstrated conveniently as a single task, for most other languages. Perhaps function composition should be a category, instead? --TBH 12:27, 28 January 2008 (MST)