Steffensen's inequality explained

Steffensen's inequality is an equation in mathematics named after Johan Frederik Steffensen.[1]

It is an integral inequality in real analysis, stating:

and g : [''a'', ''b''] → [0, 1] is another integrable function, then

b
\int
b-k

f(x)dx\leq

b
\int
a

f(x)g(x)dx\leq

a+k
\int
a

f(x)dx,

where

k=

b
\int
a

g(x)dx.

References

  1. Rabier. Patrick J.. Steffensen's inequality and

    L1

    L

    estimates of weighted integrals. Proceedings of the American Mathematical Society. 140. 2. 2012. 665–675. 0002-9939. 10.1090/S0002-9939-2011-10939-0. free.