[ge_arrow] Correct summation axis #480
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HumphreyYang
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Jul 21, 2025
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HumphreyYang
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Thanks @UdohNakamura. Great catch!
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thanks @UdohNakamura and @HumphreyYang for your review. |
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Hello,
Thank you for creating and maintaining this excellent lecture note. It has been very helpful for my studies.
I noticed a potential inconsistency between the theoretical definition of the risk-free rate and its implementation in the RecurCompetitive class.
The Issue:
In the "Markov Asset Prices" section, the price of a risk-free bond in state i is defined as$R_i⁻¹ = Σ_j Q_{ij}$ . This corresponds to summing the Q matrix across its rows (axis=1 in NumPy).
The current implementation in the risk_free_bond function uses np.sum(self.Q, 0), which sums across columns (axis=0).
The Fix:
This PR corrects the summation axis from 0 to 1 to align the code with the theoretical text.
Please let me know if I have misunderstood anything.