Quadratic Embedding Constants of Strongly Regular Graphs

We obtain an explicit formula for the quadratic embedding constant (QEC) of a strongly regular graph $\mathrm{s}\mathrm{r}\mathrm{g}(n,k,\lambda ,\mu )$ with $\mu \ge 1$. By using QEC we give a necessary and sufficient condition for a strongly regular graph to admit a quadratic embeddingin a Euclidean space.