The DNA helix generated at Veleta is a mathematical double helix.
An helix can be expressed as the parametric function:
y = r·sin(t)
z = k·t
z = k·2π → z increment after each turn.
Hence the nonparametric version (i.e. eliminitating t):
y = r·sin(k⋅z)
And therefore, both projections on the ZX or XY planes are simple sinusoid functions.
Translating the helix projection to the XY plane we get a simple sinusoid y = r⋅sin(k⋅x)
The second DNA helix can be seen as a second sinusoid with an angle shift:
y1 = r·sin(k⋅x)
y2 = r·sin(k⋅x + x0;)
where x0 ∈[0,2π] ≡ Second helix shift
Changing these parameters allows customising the DNA helix shape.