Recursive filters
| Syntax: |
FILTER\RECURSIVE x f c d
|
If the \RECURSIVE qualifier is used, the
third parameter, c, must be a vector,
and the fourth parameter, d, must also
be a vector. The data array, x, is
processed through a recursive filter. This allows for the specification of a
completely general recursive filter of arbitrary length. The values of
c are the filter coefficients which
operate on the data. The values of d
are the filter coefficients which operate on the previously made output.

where
is the length of vector
c and
is the length of vector d.
Integrating recursive filters
The trapezoidal rule integration filter:

The Leo Tick formula for integration:

See Table 7 for the trapezoidal rule and the Leo Tick formula integrating recursive filter coefficients.
Table 7: Integrating recursive filters
| type | data coefficients | output coefficients |
| Trapezoidal rule | [ 0.5; 0.5 ] | [ 1 ] |
| Leo Tick formula | [ 0.3584; 1.2832; 0.3584 ] | [ 0; 1 ] |