Classic Machine Learning Through the Eyes of an SRE — Part 2 The second algorithm I studied broke everything I'd just learned from the first. Logistic regression taught me that training means gradient descent: guess, measure error, adjust the weights, repeat until convergence. So when I opened decision trees, I went looking for the optimizer. There wasn't one. A decision tree isn't optimized the way I expected. It's grown. At each step it finds the locally best split, commits to ...