<CsoundSynthesizer>
<CsOptions>
</CsOptions>
<CsInstruments>

sr=44100
ksmps=10
nchnls=1

      gifarn init 8	; initialise integer for Farey Sequence F_8
      gires fareyleni gifarn  ; calculate length of F_8, returns 23
      ; the table length won't be a power of 2 
      ; (The length of a Farey Sequence with n > 1 is always odd)
      gilen init gires * -1   
             
      ; initialize destiniation table with 0s
      gifiltered ftgen 0, 0, gilen, 21, 1, 0

      ; initialize second destiniation table with 0s
      gifiltered2 ftgen 0, 0, gilen, 21, 1, 0
      
      ; table filtering opcode:	  dest.		source,		mode,	threshold
      ginumpassed tablefilteri 	  gifiltered,	gifarey,	1,	6
      ; the threshold parameter indicates that denominators whose weights are heavier
      ; than 6 are not passing through the filter. The weight is calculated using
      ; Clarence Barlow's function of indigestibility of a number. According to this function,
      ; higher prime numbers contribute to an increased weight of any natural integer they divide.
      ; ginumpassed is the number of elements from the source table 'gifarey'
      ; that have passed the test and which have been copied to the destination table 'gifiltered'

      ; apply a different filter:
      ginumpassed2 tablefilteri	  gifiltered2,	gifarey,	2,	5
      ; In mode=2 we again test the digestibility of the denominators of the
      ; fractions in the source table.
      ; The difference to mode=1 is that we now let pass only vaules from the
      ; source that are as heavy as the threshold or greater. 


instr 4      
      kndx init 0 ; read out elements of now filtered F_8 sequentially and print to file
      if (kndx < ginumpassed) then    
      	 kelem tab kndx, gifiltered
      	 fprintks "fareyfilter_lp.txt", "%2.6f\\n", kelem
      	 kndx = kndx+1
      endif   
endin

instr 5
      kndx init 0 ; read out elements and print to file
      if (kndx < ginumpassed2) then    
      	 kelem tab kndx, gifiltered2
      	 fprintks "fareyfilter_hp.txt", "%2.6f\\n", kelem
      	 kndx = kndx+1
      endif
endin

</CsInstruments>
<CsScore>
f1 0 23 "farey" 8
i4	0     1
i5 	0     1
e
</CsScore>
</CsoundSynthesizer>