SingleBiquadraticFilter

class lsst.ts.m2com.SingleBiquadraticFilter(a11: float, a21: float, b11: float, b21: float, num_element: int)

Bases: object

Single biquadratic filter.

Notes

The equation is:

1 + b11 z^-1 + b21 z^-2 Y(z)

H(z) = ———————– = —–

1 + a11 z^-1 + a21 z^-2. X(z)

This can be considered as the following process:

g[n-2] = b21 * x[n] - a21 * y[n] g[n-1] = g[n-2] + b11 * x[n] - a11 * y[n]

Therefore, we will have:

y[n] = x[n] + g[n-1]

Parameters

a11float

The coefficient a11 in the equation.

a21float

The coefficient a21 in the equation.

b11float

The coefficient b11 in the equation.

b21float

The coefficient b21 in the equation.

num_elementint

Number of the elements when calling the “filter()”.

Methods Summary

filter(value)	Filter the input value.
reset()	Reset the filter.

Methods Documentation

filter(value: ndarray[tuple[Any, ...], dtype[float64]]) → ndarray[tuple[Any, ...], dtype[float64]]

Filter the input value.

Parameters

valuenumpy.ndarray

Input value with the same number of elements (aka. “num_element”) when initializing this class.

Returns

value_filternumpy.ndarray

Filtered value.

reset() → None

Reset the filter.