Hello, I am encountering a very strange behaviour of einsum on my machine. I tracked the problem down to the following test code: from numpy import * T = random.random((3,10,10)) W = random.random((3,10,7,275)) print all(einsum('ij...,j...->i...',T[0],W[0]) + einsum('ij...,j...->i...',T[1],W[1]) + einsum('ij...,j...->i...',T[2],W[2]) - einsum('pij,pjts->its',T,W)< 1e-10) print sum(abs(einsum('ij...,j...->i...',T[0],W[0]) + einsum('ij...,j...->i...',T[1],W[1]) + einsum('ij...,j...->i...',T[2],W[2]) - einsum('pij,pjts->its',T,W))) On my machine the equality is not fulfilled. However, this depends, strange enough, on the dimensions of W: if the last dimension e.g. is 500 instead of 275, things work again and the equality is fulfilled. Are you encountering similar problems or is this just my machine/installation? Since I am heavily relying on einsum but can't trust my code any more, I am happily waiting for you answers. Thanks a lot! Wieland