Functional a posteriori error estimate for solution of the problem of Euler-Bernoulli beam bending

A posteriori error estimate to the problem of bending of the Euler - Bernoulli beam with variable cross-section is proposed. The estimate is derived without any additional assumptions about the structure of an approximate solution. Thus, the obtained result is suitable for error control of any approximation. Only one requirement should be satisfied - the approximation belonging to the respective energy space for the pro.