How does glmnet compute the maximal lambda value?

Question

The glmnet package uses a range of LASSO tuning parameters lambda scaled from the maximal lambda_max under which no predi

Answer 1

For your second question, look to Friedman et al's paper, "Regularization paths for generalized linear models via coordinate descent". In particular, see equation (10), which is equality at equilibrium. Just check under what conditions the numerator $S(\cdot,\cdot)$ is zero for all parameters.