Lamé Curves

Cartesian equation: (x/a)^n + (y/b)^n = 1

Click below to see one of the Associated curves.

Definitions of the Associated curves

Evolute       Involute 1       Involute 2

 Inverse curve wrt origin      Inverse wrt another circle

Pedal curve wrt origin      Pedal wrt another point

Negative pedal curve wrt origin      Negative pedal wrt another point

   Caustic wrt horizontal rays      Caustic curve wrt another point

In 1818 Lamé discussed the curves with equation given above. He considered more general curves than just those where n is an integer. If n is a rational then the curve is algebraic but, for irrational n, the curve is transcendental.

The curve drawn above is the case n = 4. For even integers n the curve becomes closer to a rectangle as n increases. For odd integer values of n the curve looks like the even case in the positive quadrant but goes to infinity in both the second and fourth quadrants.

The case n = 2/3 is the Astroid, while the case n = 3 is the (so-called) Witch of Agnesi.

The case n = 5/2 has been associated with the Danish architect and poet Piet Hein (inventor of the Soma Cube) under the name of "superellipse" and have been used for a variety of purposes, including motorway bridges and other architectural applications.


Welcome page Famous curves index
Previous curve (Famous curves) Next curve
Biographical Index Chronologies History Topics Index Birthplace Map Mathematicians of the day Anniversaries for the year Search Form Simple Search Form Search Suggestions

JOC/EFR February 1996