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

coin to bell

Open BM-05 and follow it

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)0

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.

    What the author recorded that a reader should see here.
    QuantityExpectedUnder
    kernel0 1not-applicable
  5. Set Step distribution (kernel) to 1 changes what the run starts from

  6. Set Step distribution (kernel) to 3 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.

    What the author recorded that a reader should see here.
    QuantityExpectedUnder
    kernel3 1not-applicable

These are the values the tape's author recorded, not a result this page computed. Nothing here runs the instrument. Set them yourself in BM-05 and compare what it gives you.

Every teaching tape