Constant Schedule

Why this matters

optax.constant_schedule(value) returns a callable that ignores the step and always returns value. It is the simplest possible schedule: useful as a baseline, as the “hold” phase inside a more complex chain, or when you want the familiar Optax schedule API without any decay at all.

The schedule API

Every Optax schedule is a callable schedule(step) -> lr. For a constant schedule this is trivially:

schedule = optax.constant_schedule(lr_value)
lr = schedule(step)   # always lr_value, regardless of step

Common usage pattern:

schedule = optax.constant_schedule(lr_value)
optimizer = optax.adam(learning_rate=schedule)

Common pitfalls

• A schedule is a callable — it must be called with the step to get the LR; it is not a number.
• Combining schedules with optax.join_schedules or optax.chain requires callables, not raw floats.

Inputs

• step: scalar (cast to int before calling the schedule).
• lr_value: scalar learning rate to return at every step.

Output

Scalar — the constant LR (always lr_value).