def nPr(n, r):
    return factorial(n) / factorial(n-r)
Test the speed-up rotation of Markov chain with time-varying dynamics
dataset/ETHPy150Open kdart/pycopia/core/pycopia/combinatorics.py/nPr--crossover with--dataset/ETHPy150Open bayespy/bayespy/bayespy/inference/vmp/tests/test_transformations.py/TestRotateVaryingMarkovChain.test_cost_function