Get the coefficient for the i-th power of the polynomial decomposition.
\[\theta_d = \theta(1 + d_1\theta^2 + d_2\theta^4 + d_3\theta^6 + \ldots)\]
For i=3 return the coefficient \(d_3\) associated to the \(\theta^7 = 2 * i + 1\) term.
- Parameters:
i (int) – The index of the distortion coefficient.
- Returns:
The value of the distortion coefficient.
- Return type:
float