cpsxpch

cpsxpch — Converts a pitch-class value into cycles-per-second (Hz) for equal divisions of any interval.

Description

Converts a pitch-class value into cycles-per-second (Hz) for equal divisions of any interval. There is a restriction of no more than 100 equal divisions.

Syntax

icps cpsxpch ipch, iequal, irepeat, ibase

Initialization

ipch -- Input number of the form 8ve.pc, indicating an 'octave' and which note in the octave.

iequal -- if positive, the number of equal intervals into which the 'octave' is divided. Must be less than or equal to 100. If negative, is the number of a table of frequency multipliers.

irepeat -- Number indicating the interval which is the 'octave.' The integer 2 corresponds to octave divisions, 3 to a twelfth, 4 is two octaves, and so on. This need not be an integer, but must be positive.

ibase -- The frequency which corresponds to pitch 0.0

[Note] Note

  1. The following are essentially the same

    ia  =  cpspch(8.02)
    ib     cps2pch  8.02, 12
    ic     cpsxpch  8.02, 12, 2, 1.02197503906

  2. These are opcodes not functions

  3. Negative values of ipch are allowed, but not negative irepeat, iequal or ibase.

Examples

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

Example 146. Example of the cpsxpch 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 cpsxpch.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
  ; Use a normal twelve-tone scale.
  ipch = 8.02
  iequal = 12
  irepeat = 2
  ibase = 1.02197503906

  icps cpsxpch ipch, iequal, irepeat, ibase

  print icps
endin


</CsInstruments>
<CsScore>

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


</CsScore>
</CsoundSynthesizer>


Its output should include lines like this:

instr 1:  icps = 293.666

Here is an example of the cpsxpch opcode using a 10.5 ET scale. It uses the file cpsxpch_105et.csd.

Example 147. Example of the cpsxpch opcode using a 10.5 ET scale.

<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 cpsxpch_105et.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
  ; Use a 10.5ET scale.
  ipch = 4.02
  iequal = 21
  irepeat = 4
  ibase = 16.35160062496

  icps cpsxpch ipch, iequal, irepeat, ibase

  print icps
endin


</CsInstruments>
<CsScore>

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


</CsScore>
</CsoundSynthesizer>


Its output should include lines like this:

instr 1:  icps = 4776.824

Here is an example of the cpsxpch opcode using a Pierce scale centered on middle A. It uses the file cpsxpch_pierce.csd.

Example 148. Example of the cpsxpch opcode using a Pierce scale centered on middle A.

<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 cpsxpch_pierce.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
  ; Use a Pierce scale centered on middle A.
  ipch = 2.02
  iequal = 12
  irepeat = 3
  ibase = 261.62561

  icps cpsxpch ipch, iequal, irepeat, ibase

  print icps
endin


</CsInstruments>
<CsScore>

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


</CsScore>
</CsoundSynthesizer>


Its output should include lines like this:

instr 1:  icps = 2827.762

See Also

cpspch, cps2pch

Credits

Author: John ffitch
University of Bath/Codemist Ltd.
Bath, UK
1997

New in Csound version 3.492