semitone
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## semitone

semitone — Calculates a factor to raise/lower a frequency by a given amount of semitones.

## Description

Calculates a factor to raise/lower a frequency by a given amount of semitones.

## Syntax

    semitone(x)

This function works at a-rate, i-rate, and k-rate.

## Initialization

x -- a value expressed in semitones.

## Performance

The value returned by the semitone function is a factor. You can multiply a frequency by this factor to raise/lower it by the given amount of semitones.

## Examples

Here is an example of the semitone opcode. It uses the file semitone.csd.

Example 549. Example of the semitone opcode.

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

    <CsoundSynthesizer>
    <CsOptions>
    ; Select audio/midi flags here according to platform
    ; Audio out   Audio in
    -odac           -iadc    ;;;RT audio I/O
    ; For Non-realtime ouput leave only the line below:
    ; -o semitone.wav -W ;;; for file output any platform
    </CsOptions>
    <CsInstruments>

    ; Initialize the global variables.
    sr = 44100
    kr = 4410
    ksmps = 10
    nchnls = 1

    ; Instrument #1.
    instr 1
      ; The root note is A above middle-C (440 Hz)
      iroot = 440

      ; Raise the root note by three semitones to C.
      isemitone = 3

      ; Calculate the new note.
      ifactor = semitone(isemitone)
      inew = iroot * ifactor

      ; Print out all of the values.
      print iroot
      print ifactor
      print inew
    endin

    </CsInstruments>
    <CsScore>

    ; Play Instrument #1 for one second.
    i 1 0 1
    e

    </CsScore>
    </CsoundSynthesizer>

Its output should include lines like:

    instr 1:  iroot = 440.000
    instr 1:  ifactor = 1.189
    instr 1:  inew = 523.229

## See Also

cent, db, octave

## Credits

Example written by Kevin Conder.

New in version 4.16

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