The Parabola of Fermat

Fame! Pierre de Fermat (1601-1665) is credited with generalizing work on spirals dating from Archimedes.  But he is far more famous for  Fermat's Last Theorem.   Its proof eluded great mathematicians until late in the 20th century when Andrew Wiles patiently and laboriously produced its solution. Fermat scribbled the following in his 1621 copy of a translation of  Diophantus'  Arithmetica: It is impossible to divide a cube into two cubes, or a fourth power into two fourth powers, or in general, any power greater than the second, into two like powers, and I have a truly marvelous demonstration of it.  But this margin will not contain it. In modern terms - not Latin - we would write, Interesting Facts. . . . . Archimedes (287-212 B.C.) investigated spirals centuries before Fermat, Descartes and Bernoulli, but he did not have the advantage of symbolic algebra or analytic geometry. Interestingly, both Fermat and his contemporary, René Descartes, were lawyers.    Both were also passionate lovers of number theory.   In 1636 Fermat wrote that 17,296 and 18,416 were  "amicable" numbers.  Descartes replied that he had also found another pair - 9,363,584  and  9,437,056.     As two positive integers are said to be amicable if each is the sum of the proper divisors of the other, their calculations are slightly amazing for pre-calculator or computer mathematics. Later Fermat made a slight mistake.  He sought a formula for identifying prime numbers.  He wrote others: He had calculated for n = 2, 3, and 4.  Later, Euler proved Fermat wrong by finding that when n = 5, Fermat's formula was divisible by 641.   May we suggest you try this on a calculator knowing that these gentlemen were calculating by hand. Father Mersenne, a Franciscan friar, philosopher, scientist and mathematician asked Fermat if  100,895,598,169   was prime.  Fermat promptly wrote back "no" for its was the product of  112,303  and  898,423!

Lituus' Spiral MATHEMATICA®Code	Sinusoidal Spiral MATHEMATICA@Code

Historical Sketch on Spirals

From the legendary Delian problem in antiquity to modern freeway construction, spirals have attracted great mathematical talent.  Among the more famous are Archimedes, Descartes, Bernoulli, Euler, and Fermat, but there are many more whose work has enormously influenced pure mathematics, science and engineering.

The name spiral, where a curve winds outward from a fixed point,  has been extended to curves where the tracing point moves alternately toward and away from the pole, the so-called sinusoidal type.    We find Cayley's Sextic, Tschirnhausen's Cubic, and Lituus' shepherd's (or a bishop's) crook.  Maclaurin, best known for his work on series, discusses parabolic spirals in Harmonia Mensurarum (1722).  In architecture there is the Ionic capital on a column.  In nature, the spiraled chambered nautilus is associated with the Golden Ratio, which again is associated with the Fibonacci Sequence.