Wrong inner product cost in list_decoding

[jschanck]

The value of ip_cost in the list_decoding function of cost.py is for a dimension d inner product on 32-bit integers. It should be for a dimension d/log(d) inner product. This gives us the wrong value for insert_cost and query_cost here:

eprint-2019-1161/cost.py

Lines 783 to 784 in 09d72d2

	insert_cost = filters * C(d, T2) * ip_cost * log2(d) # Alg 4, Line 5
	query_cost = filters * C(d, T1) * ip_cost * log2(d) # Alg 4, Line 8

Thanks to Leo Ducas for reporting this error (https://groups.google.com/a/list.nist.gov/g/pqc-forum/c/Fm4cDfsx65s).