for research at phd level and beyond in mathematical biology, what math courses are gonna come in handy? (beyond calculus, ODE, statistics and probability and linear algebra) I know it heavily depends on the work one wants to do, nevertheless, courses in PDEs, dynamical systems, control theory, numerical analysis, graph theory and mathematical modeling are bread and butter to the field. in addition to these subjects, are these more pure math topics like complex analysis, real analysis, abstract algebra, functional analysis used in math bio research?