1789 – 1857France
Augustin-Louis Cauchy
What does it mean for one number to get close to another?
A short story
For more than a hundred years after Newton and Leibniz, calculus had a hidden weak spot: nobody had carefully written down what getting close to really meant. Cauchy did. He gave calculus the firm ground it had been missing, and along the way he wrote hundreds of papers, so many that the journal that publishes mathematics in France was almost his personal newsletter for a while.
In their own words
What we know is not much. What we do not know is immense.
Attributed to Laplace at Cauchy's era; widely repeated in Cauchy's milieu.
The lab their idea turned into
Limit Lab
Sneak up on a value. Watch what the curve does.
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