Function nearest_multiple 

pub fn nearest_multiple(
    value: FloatType,
    unit: FloatType,
) -> Result<NearestMultiple>

The multiple of unit nearest a value that is not negative, how far off it is and which way: music21’s nearestMultiple. Half way rounds down.

use music21::common::numbertools::nearest_multiple;

let found = nearest_multiple(0.4, 0.25)?;
assert_eq!(found.multiple, 0.5);
assert_eq!(found.signed_error, -0.1);

Errors

A negative value, or one that falls between no two multiples.