Product-sum operation device, neuromorphic device, and method for determining malfunction in product-sum operation device

A product-sum operation device comprising a product operator, a sum operator, and a malfunction determiner,

• wherein the product operator includes a plurality of product operation elements connected to same line connected to the sum operator,
• each of the plurality of product operation elements is a resistance change element,
• the sum operator includes an output detector configured to detect a sum of outputs from the plurality of product operation elements,
• the malfunction determiner is configured to determine that a malfunction has occurred in at least one of the plurality of product operation elements when the sum detected by the output detector exceeds a specified value, and
• the specified value is a value equal to or greater than a maximum value of the sum that can be detected by the output detector when the plurality of product operation elements all operate normally.