Quaternions are a number system used for calculating three-dimensional motion, popular in computer graphics. And Diaz needed a crash course to help him with a consulting gig after his online video platform startup, Youcastr, had failed. He started with Wikipedia and found it was surprisingly good at explaining this complicated mathematics.
What's controversial is how Boundless creates these texts. The company trawls for public material on sites like Wikipedia and then crafts it into online books whose chapters track closely to those of top-selling college titles. In April, Boundless was sued by several large publishers who accused the startup of engaging in "the business model of theft."