A teaching tape for BM-05, Random Steps to Diffusion

coin to bell

Open BM-05 with these settings

Where it starts

The settings the tape begins from, under the constant set not-applicable. Values are the model's own, not the laboratory control's display: a radius of 5e-7 is half a micrometre.
SettingValue
Per-step RMS (stepRms)5e-7
Interval between steps (tau)0.1
Walkers (walkers)2000
Recorded steps per walker (runSteps)400
Steps shown (n)0
Asymmetric-deviation bias (bias)0.6
Step distribution (kernel)coin

What it changes, and what to expect

  1. Set Steps shown (n) to 4 changes how it is watched, not what happens

  2. Set Steps shown (n) to 16 changes how it is watched, not what happens

  3. Set Steps shown (n) to 64 changes how it is watched, not what happens

  4. Set Steps shown (n) to 400 changes how it is watched, not what happens

    Coin kernel, 400 steps: the predict prompt settles here

    The histogram at 400 coin steps is the state that settles bm-05-predict-step-shape (same-bell-shape), read from this accepted snapshot's histogram and second-moment outputs, never from stored text.

  5. Set Step distribution (kernel) to uniform changes what the run starts from

  6. Set Step distribution (kernel) to gaussian changes what the run starts from

    Gaussian kernel, same seed and step count: the same bell

    Common random numbers: same seed, same step count, a different kernel. The second moment and histogram width agree with the coin-kernel checkpoint within the declared statistical band; the shapes differ at small n and agree at n = 400.

These are the values the tape's author recorded, not a result this page computed. Nothing here runs the instrument. Open BM-05 with these settings: the link puts them in its form, and it calculates when you apply them. Compare what it gives you with what is recorded here. The settings travel in the link and the laboratory reads them as it loads, so without JavaScript it opens at its worked example instead.

What these numbers were recorded under

The identities the recorded values belong to. The same instrument run under a different seed, or under a later version of its model, gives different numbers without either set being wrong.
IdentityRecorded as
Modelbm05-host-preview-v1 version 1
Seed1905
Random-stream semanticsversion 1

Every teaching tape