Large deformation problems of Euler beams are studied. An efficient integration formula for the deflection is deduced directly from the nonlinear differential equation.

Multi-condimensional submanifold is a difficultly problem in the study, and this paper investigates the integration formula of centroaffine differential geometry of codimension 2.

This paper give a series Integration formula of indefinite integral by inverse function method, which use the relationship of a function and its inverse function and the Integration by parts.