← All parts of this equation

Equation 139 · Part 5 · The Bend an Elevator Cannot Fake

subscript

ϕ,zz h2=2 σy\phi_{,zz}\,h^2 = \sqrt2\,\sigma_y
subscript

What this part means

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

Its job in the formula

A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.

The passage around this formula

​ σ y ​ . Setting signal equal to noise, ϕ,zz\phi_{,zz}\,h2h^2 = 2\sqrt2\,σy\sigma_y , gives

Read this part in the article →

Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →

Sources cited in the article section

These citations provide research context; check each source for the exact claim it supports.