%0 Journal Article %T Modular equations for some $¦Ç$-products %A Fran£¿ois Morain %J Mathematics %D 2011 %I arXiv %X The classical modular equations involve bivariate polynomials that can be seen to be univariate with coefficients in the modular invariant $j$. Kiepert found modular equations relating some $\eta$-quotients and the Weber functions $\gamma_2$ and $\gamma_3$. In the present work, we extend this idea to double $\eta$-quotients and characterize all the parameters leading to this kind of equation. We give some properties of these equations, explain how to compute them and give numerical examples. %U http://arxiv.org/abs/1102.1606v1