process_joint

std.stats.process_joint · Level L3

The two-time joint law P(X_{t1} = s, X_{t2} = s′) of a finite-horizon process given by its complete list of paths and their probabilities.

P(X_{t1} = s, X_{t2} = s′)

Signature

process_joint(paths: i64[N, T], p: f64[N], states: f64[k], t1: i64[], t2: i64[]) → f64[k, k]

Structure

The function as NOVA stores it: one box per input, operation and output, and arrows that carry values. A double border marks another library function this one runs — called once, or by Scan once per element; select it to open that function.

pf64[N]t1i64[]pathsi64[N, T]statesf64[k]t2i64[]ReshapepcTransposeptIotao1_yIotao2_yGatherr1Reshapeo1_rGatherr2Reshapeo2_rCasto1_fCasto2_fReshapeo1_cReshapeo2_cEqualo1Equalo2Multiplyw1Transposew1tMatMulJJf64[k, k]
  • input
  • operation
  • constant
  • call
  • output

Verification

  • Signature proven by NOVA’s shape solver, for every size.
  • Equal to the reference the masses of the paths through s at t1 and s′ at t2 in exact rational arithmetic, on all 40 test cases.
  • All 1,008 float64 results are exact: the error is zero.
  • Interpreter and NumPy backend return bit-identical results.
  • At float32 too: the 40 test cases rounded to float32, and 40 of them exact, with zero error.
Accuracy in detail
correctly rounded (the float64 nearest the exact value)
100%
bit-equal to the NumPy formula in float64
100%
largest error, in units in the last place
0

Identity

Calls
—
Called by
—
sha256:2f6c3feec76ac60b4647bbc0b6565b5b53394bcfd2a4867dee12b7a4328d8803

The semantic hash of the graph. It changes when the program changes, and never when only its documentation does.

Control handle

Symbol
Ω:std.stats.process_joint · Ω:process_joint
Pins
sha256:f1ad5604485e08761ad93359dd3eca8a9efdcab962b9f3a1b66c2714445096aethis graph alone
Evidence
sha256:a0adb972331cf8c163ce1647c12de45b4dc54f098813ff71fad4ed2260a3e463the hash of its verification record
Needs
no capability: a pure function

Through NOVA’s control layer, the symbol launches this function only while the program still matches what it pins: a change to this graph, or to any graph it reaches, needs a migration first.

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