Color: from spectrum to tristimulus

Introduction

Edit 30 Oct 2009:
This is the first post about an example on p. 160 of Wyszecki & Stiles (see the bibliography).

and find another edit about the components wrt the dual basis.
End edit.

As always, if my chatter is confusing, just start following the examples.

In a sense, what I am about to do now is one of the most important color calculations I will show you.

How do we get from a spectrum to tristimulus values?