Mathematician:Karl Theodor Wilhelm Weierstrass

Mathematician

German mathematician whose main work concerned the rigorous foundations of calculus.

Known as "the father of modern analysis".

Champion beer-drinker and expert fencer.

Nationality

German

History

• Born: 31 Oct 1815, Ostenfelde, Westphalia (now Germany)
• Died: 19 Feb 1897, Berlin, Germany

Achievements

• Pioneered the $\epsilon-\delta$ definition of continuity.
• Was able thereby to formulate proofs of the Bolzano-Weierstrass Theorem (which had been proved earlier, independently of Weierstrass, by Bernhard Bolzano), the Intermediate Value Theorem and the Heine-Borel Theorem.
• Made significant advancements in the field of calculus of variations.

Theorems and Definitions

• Weierstrass E-Function
• Weierstrass Elementary Factor
• Weierstrass's Elliptic Function
• Weierstrass Function

• Bolzano-Weierstrass Theorem (independently of Bernhard Bolzano)
• Enneper-Weierstrass Parameterization (with Alfred Enneper)
• Hermite-Lindemann-Weierstrass Theorem (with Charles Hermite and Ferdinand von Lindemann)
• Sokhotski-Weierstrass Theorem (with Yulian Vasilievich Sokhotski)
• Stone-Weierstrass Theorem (with Marshall Harvey Stone) (a generalization of the Weierstrass Approximation Theorem)

• Weierstrass Approximation Theorem
• Weierstrass Extreme Value Theorem
• Weierstrass Factorization Theorem
• Weierstrass Intermediate Value Theorem (also known as Bolzano's Theorem for Bernhard Bolzano)
• Weierstrass M-Test
• Weierstrass's Necessary Condition
• Weierstrass Preparation Theorem
• Weierstrass Product Inequality
• Weierstrass Product Theorem
• Weierstrass Substitution
• Weierstrass's Theorem

• Weierstrass-Casorati Theorem (with Felice Casorati)
• Weierstrass-Erdmann Corner Conditions (with G. Erdmann)

Results named for Karl Theodor Wilhelm Weierstrass can be found here.

Definitions of concepts named for Karl Theodor Wilhelm Weierstrass can be found here.

Publications

• 1854: Zur Theorie der Abelschen Funktionen (J. reine angew. Math. Vol. 47: 289 – 306)
• 1856: Theorie der Abelschen Funktionen
• 1894: Abhandlungen-1
• 1897: Abhandlungen-2
• 1902: Vorl. ueber die Theorie der Abelschen Transcendenten
• 1915: Abhandlungen-3
• 1927: Vorl. ueber Variationsrechnung

Notable Quotes

A mathematician who is not also something of a poet will never be a complete mathematician.

-- Quoted in 1937: Eric Temple Bell: Men of Mathematics: They Say: What Say They? : Let Them Say

The infinite emptiness and boredom of those years would have been unendurable without the hard work that made me a recluse -- even if I was rated rather a good fellow by the circle of my friends among the Junkers, lawyers, and young officers of the community ... The present offered nothing worth mentioning, and it was not my custom to speak of the future.

Critical View

You should study with Weierstrass in Berlin; he is the master of us all.

-- Charles Hermite to Gösta Mittag-Leffler

Sources

• John J. O'Connor and Edmund F. Robertson: "Karl Theodor Wilhelm Weierstrass": MacTutor History of Mathematics archive

• 1937: Eric Temple Bell: Men of Mathematics ... (previous) ... (next): They Say: What Say They? : Let Them Say
• 1937: Eric Temple Bell: Men of Mathematics: Chapter $\text{XXII}$
• 1939: E.G. Phillips: A Course of Analysis (2nd ed.) ... (previous) ... (next): Chapter $\text {I}$: Number: $1.1$ Introduction
• 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): Weierstrass, Karl Theodor Wilhelm (1815-97)
• 1992: George F. Simmons: Calculus Gems ... (previous) ... (next): Chapter $\text {A}.33$: Weierstrass ($\text {1815}$ – $\text {1897}$)
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): Weierstrass, Karl Theodor Wilhelm (1815-97)
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): Weierstrass, Karl Theodor Wilhelm (1815-97)
• 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): Weierstrass, Karl (Theodor Wilhelm) (1815-97)