possible discuss existence higher order derivatives well finding derivative derivative function one classify functions '''' 'differentiability class''''' class math c math sometimes math c ab math indicate interval applicability consists continuous functions class math c math consists differentiable functions whose derivative continuous functions called '''''continuously differentiable''''' thus math c math function exactly function whose derivative exists class math c math general classes '' math c k math '' defined recursively declaring math c math
Formal science Mathematics Pure mathematics Analysis Real analysis