 Fix "p" and "q" with , and choose a basis ω1, ..., ωs for the harmonic forms of type .The period matrix of "X"0 with respect to these bases is the matrix

The entries of the period matrix depend on the choice of basis and on the complex structure.The δs can be varied by a choice of a matrix Λ in , and the ωs can be varied by a choice of a matrix "A" in .