Electronic Journal of Differential Equations, Vol. 2002(2002), No. 86, pp. 1-6. Title: An embedding norm and the Lindqvist trigonometric functions Authors: Christer Bennewitz (Lund Univ., Sweden) Yoshimi Saito (Univ. of Alabama at Birmingham, USA) Abstract: We shall calculate the operator norm $\|T\|_p$ of the Hardy operator $Tf = \int_0^x f $, where $1\le p\le \infty$. This operator is related to the Sobolev embedding operator from $W^{1,p}(0,1)/\mathbb{C}$ into $W^p(0,1)/\mathbb{C}$. For $1