Scale types

Choose the progression according to the relationship between consecutive values.

Scale	Relationship	Typical use
Modular	Multiply by one ratio	Type sizes, proportional spacing
Linear	Add one increment	Baseline grids, fixed spacing
Fibonacci	Follow Fibonacci numbers	Integer rhythms and counts
Multi-strand	Interleave several modular scales	Multiple coordinated bases

Every type implements ScaleInterface, so application code can accept any scale while using get(), stepOf(), snap(), and range().

<?php
use Alto\Scale\ScaleInterface;

function tokens(ScaleInterface $scale): array
{
    return $scale->range(-2, 5);
}

The shared contract does not imply identical domains. Modular and multi-strand scales require positive values for logarithmic lookup. Linear scales can cross zero. Fibonacci lookup maps non-positive values to step zero.