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Double Helix Structure

The DNA molecule exists as a double helix, with two antiparallel strands held together by hydrogen bonds between base pairs.
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The statement of the theorem

Let ri\mathbf{r}_i be the spatial coordinates of the ii-th base pair center, and let NN be the total number of base pairs. The double helix structure is defined by the coordinates R(i)\mathbf{R}(i) of the ii-th unit, parameterized by the helical index i∈Zi \in \mathbb{Z}. The coordinates must satisfy the following geometric constraints:\nR(i)=R0+ih(vz)+12π(vxcos⁡(2πiP)+vysin⁡(2πiP))\mathbf{R}(i) = \mathbf{R}_0 + \frac{i}{h} \left( \mathbf{v}_z \right) + \frac{1}{2\pi} \left( \mathbf{v}_x \cos\left(\frac{2\pi i}{P}\right) + \mathbf{v}_y \sin\left(\frac{2\pi i}{P}\right) \right) \nwhere PP is the helical pitch, hh is the rise per base pair, and vx,vy,vz\mathbf{v}_x, \mathbf{v}_y, \mathbf{v}_z are orthogonal unit vectors defining the axis and cross-section of the helix. Furthermore, the distance between paired bases must be constrained by the base pairing rules.
Source: Wikipedia