I've just cracked open a biophysics textbook and it's all fine up until the introduction of the letter C in a wavefunction equation, and declaring C₁= ±C₂

I've had lectures on eigenfunctions etc. before and no recollection of what C is, and it's not introduced earlier in the book (Biophysics, Pattabhi and Guatham, 2002).

A scan of the section in question (1.4) is below:

![enter image description here][1]

Anyone care to enlighten me? [1]: https://i.sstatic.net/1I0at.png