we know that a complex torus,which is algebraic,is called abelian variety.Recently i see another definition.Let $\mathbb{C}^n/\Lambda$ be a complex torus,where $\Lambda$ is a lattice of $\mathbb{C}^n$.$\mathbb{C}^n/\Lambda$ is abelian variety when there is a real skew-symmetric bilinear $E$ form on $\mathbb{C}^n$,satisfying

1)$E(iX,Y)=E(iY,X)$ for $X,Y\in\mathbb{C}^n$

2)$E(iX,X)>0$ for nonzero $X\in\mathbb{C}^n$

3)$E(X,Y)\in\mathbb{Z}$ for $X,Y\in\Lambda$

How can i see the equivalence?