Principle 16: Partial or excessive action

"Do a little less" or "Do a little more"

We want to draw a line on the computer screen, but our current algorithm, which involves multiplication and division, is too slow.

Currently our code is (assuming x is the major axis of the line):

1 ylen = (yend - ystart);
2 xlen = (xend - xstart);
3 for (x = xstart; x < xend; x++) {
4   y = x * ylen / xlen;
5   plot (x, y);
6 }