#include "ode_o1.h" // a * df/dt + b * f = c // (f(t + dt) - f(t)) / dt = g(f(t)) => f(t + dt) = f(t) + dt * g(f(t)). double advance(double (*g)(double, void *), double f0, double dt, void *state) { return f0 + dt * g(f0, state); }