tablefilteri — Filters a source table and writes result into a destination table.

This opcode can be used in order to filter values from function tables following certain algorithms. The filtered output is written into a destination table and the number of elements that have passed the filter is returned.

*inumpassed* -- the number of elements that
have passed the filter.

*iouttable* -- the number of the table containing the values that have passed.

*iintatble* -- the number of the table used as filter input.

*imode* -- mode of the filter:

- 1 -- tests the weight of the denominators of the fractions in the source table. Letting pass only values from the source that are less heavy than the weight of the threshold.
- 2 -- tests the weight of the denominators of the fractions in the source table. Letting pass only values from the source that are heavier than or equal to the weight of the threshold.

*iparam* -- integer threshold parameter for
the filter. It means that denominators whose weights are heavier
than the weight of this threshold are not passed through the
filter. The weight of an integer 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. The order of the
first 16 integers according to their indigestibility is: 1, 2,
4, 3, 8, 6, 16, 12, 9, 5, 10, 15, 7, 14.

Here is an example of the tablefilteri opcode. It uses the file *tablefilter.csd*.

**Example 900. Example of the tablefilteri opcode.**

See the sections *Real-time Audio* and *Command Line Flags* for more information on using command line flags.

<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 gifarey ftgen 200, 0, gilen, "farey", gifarn, 0 ; 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> i4 0 1 i5 0 1 e </CsScore> </CsoundSynthesizer>