dm_filter Module

IIR filter module, based on FORTRAN 77 procedures by David Harris:

Harris, D. (1990): XAPiir. A Recursive Digital Filtering Package. Technical Report. Lawrence Livermore National Laboratory. DOI: doi.org/10.2172/6416972

Uses

- dm_kind
- dm_const
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Used by

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Variables

Type	Visibility	Attributes		Name		Initial
integer,	public,	parameter	::	FILTER_MAX_ORDER	=	8	Max. order (number of poles).
integer,	public,	parameter	::	FILTER_BESSEL	=	1	Bessel.
integer,	public,	parameter	::	FILTER_BUTTERWORTH	=	2	Butterworth.
integer,	public,	parameter	::	FILTER_CHEBYSHEV1	=	3	Chebyshev Type I.
integer,	public,	parameter	::	FILTER_CHEBYSHEV2	=	4	Chebyshev Type II.

Functions

public pure elemental function dm_filter_is_valid(filter) result(valid)

Returns .true. if prototype is a valid filter enumerator:

Arguments

Type	Intent	Optional	Attributes		Name
integer,	intent(in)			::	filter	Filter enumerator (`FILTER_*`).

Return Value logical

Subroutines

public pure subroutine dm_filter_high_pass(filter, data, order, cutoff, ts, zp, attenuation, transition)

Arguments

Type	Intent	Optional	Attributes		Name
integer,	intent(in)			::	filter	Filter enumerator (`FILTER_*`).
real(kind=r8),	intent(inout)			::	data(:)	Sequence to be filtered.
integer,	intent(in)			::	order	Order (#poles), not to exceed `FILTER_MAX_ORDER`.
real(kind=r8),	intent(in)			::	cutoff	Low-frequency cut-off of filter [Hz].
real(kind=r8),	intent(in)			::	ts	Sampling interval [sec].
logical,	intent(in)			::	zp	Zero phase filtering if `.true.`, else single pass filtering.
real(kind=r8),	intent(in),	optional		::	attenuation	Chebyshev stopband attenuation factor.
real(kind=r8),	intent(in),	optional		::	transition	Chebyshev transition bandwidth (fraction of low-pass prototype passband width).

public pure subroutine dm_filter_low_pass(filter, data, order, cutoff, ts, zp, attenuation, transition)

Arguments

Type	Intent	Optional	Attributes		Name
integer,	intent(in)			::	filter	Filter enumerator (`FILTER_*`).
real(kind=r8),	intent(inout)			::	data(:)	Sequence to be filtered.
integer,	intent(in)			::	order	Order (#poles), not to exceed `FILTER_MAX_ORDER`.
real(kind=r8),	intent(in)			::	cutoff	High-frequency cut-off of filter [Hz].
real(kind=r8),	intent(in)			::	ts	Sampling interval [sec].
logical,	intent(in)			::	zp	Zero phase filtering if `.true.`, else single pass filtering.
real(kind=r8),	intent(in),	optional		::	attenuation	Chebyshev stopband attenuation factor.
real(kind=r8),	intent(in),	optional		::	transition	Chebyshev transition bandwidth (fraction of low-pass prototype passband width).