RETRIEVAL DEVICE FOR RETRIEVING HIGH DIMENSIONAL FEATURE VECTOR AND PROGRAM

PROBLEM TO BE SOLVED: To provide a retrieval device for retrieving a feature vector approximating a query feature vector from a set of high dimensional feature vectors and the like.SOLUTION: A retrieval device includes: residual quantization means that has F quantizers of each m-th stage (2≤m≤M) sequentially formed from one quantizer of a fist stage (m=1) in a multistage structure and is configured such that a residual vector ybetween a vector yinput to the quantizers in the m-th stage and a vector youtput from the quantizers is input to subsequent quantizer of (m+1)-th stage while any one quantizer f (1≤f≤F) is being selected for each m-th stage; and retrieval means that calculates inner products (s=x d) of a query vector x and all representative vectors dof a residual codebook and retrieves a registration vector y approximating an approximate vector y, more specifically having a short distance therebetween, calculated from a cumulative sum of the inner products on the basis of an identifier lstring under predetermined conditions.