RTF_CREATE_CHEBYCHEV(3) 					 rtfilter library					   RTF_CREATE_CHEBYCHEV(3)

NAME

       rtf_create_chebychev, rtf_create_butterworth - Creates IIR Chebychev and Butterwoth filters

SYNOPSIS

       #include <rtf_common.h>

       hfilter rtf_create_chebychev(unsigned int nchann, int proctype,
				    double fc, unsigned int num_pole,
				    int highpass, double r);
       hfilter rtf_create_butterworth(unsigned int nchann, int proctype,
				      double fc, unsigned int num_pole,
				      int highpass);

DESCRIPTION

       rtf_create_chebychev()  creates	a IIR chebychev filter processing nchann channels of data type specified by proctype with fc as normalized
       cutoff frequency, whose the Z-transform has num_pole poles and whose the impulse response has a ripple of r This latter is expressed as the
       ratio  between  the  overshoot  (difference  between  the max value of the response to a unit step and the unit length) and the unit length
       (ratio not expressed in decibels).

       rtf_create_butterworth() is the same as rtf_create_chebychev() but creates a butterworth filter (which a special case of a chebychev filter
       with a ripple of 0).

       A  normalized  frequency is the ratio between the absolute frequency and the sampling frequency (i.e. a value of 1.0 refers to the sampling
       frequency).

       If highpass is 0, it specifies the filter should be a lowpass. If highpass is non-zero, the should be a highpass.

RETURN VALUE

       Returns the handle to the created filter in case of success, NULL otherwise.

SEE ALSO

       rtf_create_filter(3), rtf_destroy_filter(3)

EPFL
								       2010						   RTF_CREATE_CHEBYCHEV(3)