In mathematics, the Legendre forms of elliptic integrals, F(φ,k), E(φ,k) and P(φ,k,n) are defined by

<math>F(\phi,k) = \int_0^\phi \frac{1}{\sqrt{1 - k^2 \sin^2(t)}} dt,<math>

<math>E(\phi,k) = \int_0^\phi \sqrt{1 - k^2 \sin^2(t)}\,dt,<math>

and

<math>P(\phi,k,n) = \int_0^\phi \frac{1}{(1 + n \sin^2(t))\sqrt{1 - k^2 \sin^2(t)}}\,dt.<math>