Calculation device including multiple calculation cores

A calculation device configured to output a solution of an optimization problem with N discrete variables, where N is an integer equal to or greater than 2, the calculation device comprising:

• P calculation cores each connected to a network, where P is an integer equal to or greater than 2 and less than N, wherein
• each of the P calculation cores is exclusively assigned with some of N virtual oscillators, each of the N virtual oscillators representing a virtual particle having one degree of freedom and being a simulation target,
• the N virtual oscillators correspond one-to-one with the N discrete variables and virtually change in position and momentum over time in one dimensional direction,
• the P calculation cores are configured to calculate N first variables representing the position and N second variables representing the momentum in the N virtual oscillators, sequentially for each of time steps from an initial time to an end time,
• the P calculation cores are configured to output values based on the N first variables at the end time as values based on the solution of the optimization problem,
• a kth calculation core among the P calculation cores, where k is an integer equal to or greater than 1 and less than P,
• is assigned with M virtual oscillators among the N virtual oscillators, where M is an integer equal to or greater than 1 and less than N, and
• at each of the time steps, is configured to calculate M first variables corresponding to the assigned M virtual oscillators among the N first variables and M second variables corresponding to the M virtual oscillators, the kth calculation core includes:
• a receiving circuit configured to receive, at each of the time steps, N−M first variables at a previous time step calculated by P−1 calculation cores other than the kth calculation core among the P calculation cores, portion by portion sequentially, via the network;
• an interaction circuit configured to calculate, at each of the time steps, M intermediate variables corresponding to the M virtual oscillators, based on the N first variables at the previous time step;
• a time evolution circuit configured to calculate, at each of the time steps, the M first variables and the M second variables at a target time step, based on the M first variables at the previous time step, the M second variables at the previous time step, and the M intermediate variables;
• and
• a transmitting circuit configured to transmit, at each of the time steps, the M first variables calculated by the time evolution circuit to the P−1 calculation cores via the network,
• the interaction circuit includes an intermediate variable memory configured to store the M intermediate variables under calculation,
• at each of the time steps, the interaction circuit is configured to start calculation of the M intermediate variables before the receiving circuit completes reception of all of the N−M first variables at the previous time step,
• the intermediate variable memory includes M registers corresponding to the M intermediate variables,
• each of the M registers is written with a value under calculation in a corresponding intermediate variable,
• two or more registers among the M registers are connected in series to function as a shift register configured to transfer a stored value to an adjacent register in a series direction, or are arranged in a plurality of columns and connected for each column to function as a plurality of shift registers configured to transfer a stored value to an adjacent register in a series direction for each column, and
• the interaction circuit is configured to allow the two or more registers to function as the shift register or the shift registers to supply the M intermediate variables to the time evolution circuit.