11 Calculus

Calculus is the mathematics of approximation. Here are the ideas that are fundamental to the study of calculus.

The limit. A limit is a value: the number a function approaches as its input gets arbitrarily close to a point.

The derivative. The derivative is a rate: the instantaneous rate of change of a function at a point. Geometrically it is the slope of the best straight-line approximation to the curve there.

The fundamental theorem of calculus. Differentiation and integration are inverse operations. Differentiation is the operation of finding a rate. Integration is the operation of accumulating a quantity. The fundamental theorem is the statement that these two operations undo each other.

11.2 References

  1. Hubbard, J. H., & Hubbard, B. B. Vector Calculus, Linear Algebra, and Differential Forms: A Unified Approach. — calculus as what becomes true in the limit, and the derivative as the best linear approximation.
  2. Griffel, D. H. Applied Functional Analysis. — elementary calculus as the tangent line giving the best approximation to a curve at a point.
  3. Stewart, J. Calculus: Early Transcendentals. — the limit as the value a function approaches.
  4. Needham, T. Visual Differential Geometry and Forms. — the fundamental theorem as the inverse relation of differentiation and integration.