Calculator and calculation method

A calculation method comprising:

• dividing, by a calculator including:
• a plurality of registers each including a plurality of sub-registers that hold a plurality of pieces of data for use in operation, respectively;
• an operator that executes, in parallel, operations of the pieces of data held in the plurality of sub-registers, respectively;
• and a memory that is configured to hold a first vector and a plurality of second vectors to be compared with the first vector, each of the plurality of second vectors into sub-vectors each having a size equal to a size of each of the sub-registers;
• sequentially arranging a plurality of sub-vector groups each including the sub-vectors of the plurality of second vectors in a readable manner in the memory in units of sub-vector groups;
• repeatedly executing, for all sub-vectors of the first vector, a first process of transferring one of sub-vectors of the first vector held in the memory to a plurality of sub-registers of a first register among the plurality of registers, a second process of transferring the sub-vector group of the plurality of second vectors corresponding to the transferred sub-vector of the first vector to a plurality of sub-registers of a second register among the plurality of registers, the sub-vector group being held in the memory, and a third process of calculating and integrating numbers of mismatches between bit values of the sub-vectors held in the sub-registers corresponding to each other in the first register and the second register;
• and
• determining a second vector in which an integrated value of the calculated numbers of mismatches is smallest to be a closest matching vector.