θ4⁡(z|τ)=θ4⁡(0|τ)⁢∏n=1∞sin⁡((n-12)⁢π⁢τ+z)⁢sin⁡((n-12)⁢π⁢τ-z)sin2⁡((n-12)⁢π⁢τ).