nf – determine normal form for successive vertical sonorities in Humdrum inputs
`` nf [inputfile ...] [> outputfile.nf]``
The nf command is used to determine the normal form for any of five set-theory related inputs: pitch (**semits), pitch-class (**pc), prime form (**pf), interval-class vector (**iv), or Fortean set name (**pcset).
“Normal form” is a standardized way of representing the pitch material for any arbitrary set of pitches. Normal form provides the most intervallically compact spelling of the pitch-classes evident in a given sonority. It is analogous to rearranging notes in a chord so that the spelling is in root position, close position, with duplicate pitch-classes eliminated. By way of example, a D major chord (in any inversion, with any spelling) will have the normal form: 2,6,9 – namely, the pitch-classes D, F#, A (as opposed to 6,9,2 or 2,9,6). See REFERENCES below.
When provided with **semits or **pc inputs, nf treats each input record as a set of pitches. Unisons and other pitch-class duplications have no effect on the output. Rests within a set of pitches are ignored; where an input record consists solely of one or more rests, a null-token is output.
The nf command is able to translate any of the representations listed below. For descriptions of the various input representations (including **nf) refer to Section 2 (Representation Reference) of this reference manual.
It is recommended that output files produced using the nf command should be given names with the distinguishing `.nf’ extension.
**iv interval-class vector representation **nf normal form representation **pc pitch-class representation **pcset Fortean pitch-class set name **pf prime form representation **semits equal-tempered semitones with respect to middle C=0 (e.g. 12 = C5)
Input representations processed by **nf*.*
The nf command provides only a help option:
-h displays a help screen summarizing the command syntax
Options are specified in the command line.
The following command outputs the normal form for the sets formed by successive sonorities in the input file opus24. The input may be pitches, pitch-classes, Fortean set names, etc.
`` nf opus24 > opus24.nf``
DOS 2.0 and up, with the MKS Toolkit. OS/2 with the MKS Toolkit. UNIX systems supporting the Korn shell or Bourne shell command interpreters, and revised awk (1985).
The nf command is a shell script that invokes pcset -n.
Allen Forte, The Structure of Atonal Music. New Haven: Yale University Press, 1973.
John Rahn, Basic Atonal Theory. New York: Longman Inc., 1980.
Straus, J. Introduction to Post-Tonal Theory. Englewood Cliffs, N.J.: Prentice Hall, 1990.
- **Pertinent description in the Humdrum User Guide**
- **Index to Humdrum Commands**
- **Table for Contents for Humdrum User Guide**