In a text describing mathematically an algorithm, there is a vector $y_l$ (local y-axis) which is computed, but must be subsequently adjusted to avoid numerical drift. I've considered a few possibilities to write it:
- using APL-like arrow, $ y_l\leftarrow y_l-x_l(y_l\cdot x_l)$,
- with Pascalesque $y_l:=y_l-x_l(y_l\cdot x_l)$,
- introducing an extra $y_l'$ first, then just say $y_l=y_l'-x_l(y_l'\cdot x_l)$.
I find 1. the most readable, 3. the most correct and I've seen 2. several times. The text does not otherwise use algorithmical notation (such as pseudo-code). Which of them to pick?