Formulas Are Just Syntax
You've crossed eleven tracks. Vectors, matrices, eigen, logarithms, probability, normality, regression, calculus, backprop. You met dozens of formulas. The temptation is to memorize them. Don't.
A formula is just syntax. It's the punctuation of an idea. Like Python syntax — you can look it up. Like English grammar rules — you internalize them by using the language, not by reciting tables. The same is true of math. The formula is beautiful, but you didn't take this quest to memorize it. You took it to understand why a function's slope tells you which way to nudge weights.
What Computers Can't Do for You
NumPy can compute any derivative. PyTorch's autograd handles backprop perfectly. scipy.linalg solves any system. What no computer can do is decide why you'd take that derivative in the first place. The "why" is the conceptual layer — the mold behind the instances, the verb behind the noun.
Concepts > formulas. If you can explain the shape of an idea to a friend in a sentence — "the dot product measures alignment," "the gradient points uphill," "softmax turns logits into probabilities" — the formula will reassemble itself when you need it.