| 摘要 |
A storing unit includes a predetermined number of present value buffers that store the present value in time series, and a predetermined number of section-representative-value buffers that store a section representative value calculated based on the present value belonging to a predetermined section included in the monitoring period in time series. A storage control unit performs, when the present value is acquired, a control for storing data in the present value buffers and the section-representative-value buffers. A calculating unit calculates a period representative value of the monitoring period based on the present value and the section representative value stored in the storing unit.
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