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## Transposition

The transpose and addtranspose parameters can be used to transpose the pitches for a staff or the whole score. The following table shows what transposition values to use for different intervals.

halfsteps | tranposition | alternate transposition
0 | perfect 1 | diminished 2
1 | augmented 1 | minor 2
2 | major 2 | diminished 3
3 | augmented 2 | minor 3
4 | major 3 | diminished 4
5 | augmented 3 | perfect 4
6 | augmented 4 | diminished 5
7 | perfect 5 | diminished 6
8 | augmented 5 | minor 6
9 | major 6 | diminished 7
10 | augmented 6 | minor 7
11 | major 7 | diminished 8

This table continues in a similar way for intervals beyond an octave. For each number of halfsteps you want to transpose, there is more than one way the transpose and addtranspose parameters can be specified, as shown by this table. This allows to you control whether a sharp key or a flat key is to be used in cases where there is a choice. For example, if the key signature has three sharps, and you want to transpose up two halfsteps, you could say either

    	transpose = up maj 2

or

    	transpose = up dim 3

The first will result in a key of five sharps, and the second will result in seven flats. These are equivalent keys; in major for example, they are B and C flat, which are the same note. It is up to you to choose the way you would like it to be printed. But no key is allowed to have more than seven sharps or flats, so in most cases only one of the ways will result in a valid key, and the other way will result in an error message.

The transpose and addtranspose parameters are allowed in score and staff contexts, so they can be set to different values on different staffs, and on the score as a whole. This is useful for printing scores where some of the instruments are transposing instruments (like B-flat clarinet). You can set the transpose parameter on specific staffs to appropriate values for the transposing instruments. Then if you decide you want to move the entire score to a new key, you can set the addtranspose parameter in score context. You can enter all the music at true pitch, but print the score and/or the individual parts with the correct transposition.

Another use for setting different transposition values is the following trick, useful in guitar music for printing both the real chords and chords for capo. Say, for example, you have a song that is in B flat, but the guitar is to use a capo on the third fret, and play in the key of G. You could define the following macro to print both versions of a chord, the capo version above the real version:

    define CHORD(COUNT, NAME)

    	bold chord all: COUNT `NAME`;     // chord for capo
    	ital(8) chord 1: COUNT `NAME`;    // real chord
    @

Then, set these transpositions:

    score   transpose = down minor 3	// transpose score for capo
    staff 1 transpose = up perfect 1	// override score transposition

and similarly for any other staffs. Then, wherever you want to print a chord, say (for example)

    CHORD(3,Dm)

This will print both versions of the chord above count 3 of the measure. For the top chord it will transpose this to Bm, the capo chord. For the bottom chord it will leave it as Dm, the real chord.

For MIDI purposes, if your MIDI player supports altered tunings, the a4freq parameter could be used to get the effect of transposing all the voices.

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