As a follow up: I want to pursue a math degree study. What course titles and textbooks starting at the calculus level do you guys recommend? I want enough math chomps to then go onto a PhD in ML.
Linear Algebra (which is what you really need): Gilbert Strang - Linear Algebra and its applications
These two are all you need, with which you'll get a solid base. Then you're good to go on your own. These two combined are about 4 semesters worth of work. But if you really focus, I think you can get them done in a little less than 6 months.
If you want a 'just what I need' approach, Khan Academy.
For self-study, you don't necessarily need to follow the usual progression of math classes that start at calculus. It's more important to get comfortable with linear algebra than calculus, especially the way a lot of intro calculus courses focus on calculating integrals and derivatives. Maybe it's not the best message, but the worst grades in my math degree were in the intro calculus classes.
I don't remember what intro linear algebra books I used, but my college uses this: https://www.math.ucdavis.edu/~linear/ (I took the class before this free textbook was developed).
Linear Algebra (which is what you really need): Gilbert Strang - Linear Algebra and its applications
These two are all you need, with which you'll get a solid base. Then you're good to go on your own. These two combined are about 4 semesters worth of work. But if you really focus, I think you can get them done in a little less than 6 months.
If you want a 'just what I need' approach, Khan Academy.