Landen's formula is given by
 |
where 
are Jacobi theta functions. This transformation
was used by Gauss to show that elliptic integrals
could be computed using the arithmetic-geometric
mean.
Landen's Formula
See also
Jacobi Theta FunctionsExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Landen's Formula." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/LandensFormula.html