I want to play this piece originally for cello. I need this music for a flute. Cello and flutes are both in the key of C, but cello is a non transposing instrument in the bass clef. How can I do this?
You may very well find yourself having to arrange the piece, rather than transpose/transcribe it. As @guidot notes, the range of the instruments differ not only in locus, but in width - the 'cello has a wider easily-usable range than the flute, as well as being lower. That being said, there are few things that might need to be considered:
- You should look at the lowest note actually played in the 'cello part to figure out your transposition (by assigning that note to low C on the flute): not all 'cello parts use the open C string. Even then, you may need to adjust the transposition level for ease of fingering.
- Certain figurations are going to idiomatic to the 'cello, but possibly much less so to the flute. For instance, arpeggios across the strings: some of these might span a range that is awkward across the breaks. You might need to modify the figuration into something more idiomatic for the flute.
- Similarly, certain effects native to the 'cello might need to be given flute equivalents, for instance sul ponticello or harmonics, perhaps replacing these with flutter-tonguing and "white tone" (senza vibrato) respectively. You may need to figure out how to deal with 'cello chords. (Perhaps by gracing up to the top note? Changing accompanying parts? Is there a suitable multiphonic, and is that feasible for the intended performers?)
- If it is an accompanied piece, you may well have to adjust the accompaniment, even if you remain in the same key as the original. The ambitus of the 'cello means that it will normally be accompanied as a tenor instrument (which is fairly easily hoisted to the flute's range, although you may need to fix parallel fifths if the idiom precludes them), but it's a rare composer who will resist contrasting that texture with one using the 'cello as a bass, and that is not something your flute part can manage. This also means that the chord inversion may change at times, and that can sometimes break the harmony.
- Finally, as @guidot also mentions in his comment, because of the 'cello's wider range, you may have to change the (relative) register of certain passages.
Whether you need to arrange the music to this extent is going to depend on the complexity and range of the 'cello part, and on its relationship to the accompaniment, but do bear in mind that it is quite possible (the instruments being so different in type) that you will find it wiser to give an impression of the piece rather than a straight transposition; for music of even modest complexity, it even becomes quite likely.
It will depend on the range of the piece in question, but a simple way would be to take the highest line away from the bass clef and put an extra one at the bottom. Either mentally of by re-writing. This would put every note into a treble clef situation, and be simple to do. And hopefully simple to read. The only problem then, is, as I say, the range may not be good for you or the flute.
Or - you could leave the dots where they are, and pretend that the bass clef is actually treble, but then you'd be playing in a different key,and have to compensate by changing the key signature to a key a minor third higher. Which again, may take you out of range. Otherwise, as Dom states, transpose completely. It depends also whether you want to keep it in the same key as original, which should be a possibility.