The original version of this story appeared in Quanta Magazine. Calculus is a powerful mathematical tool. But for hundreds of years after its invention in the 17th century, it stood on a shaky ...

In the late 19th century, Karl Weierstrass invented a fractal-like function that was decried as nothing less than a “deplorable evil.” In time, it would transform the foundations of mathematics.

Easily calculating limits, directly from an intuitively clear definition, using the same basic procedure for every type of limit, with a high level of student success. The impossible dream? Not if we ...