PURPOSE: To shorten the working time of a computer by performing arithmetic processing in a longer period by effectively using the result of arithmetic operation performed in a short period.

CONSTITUTION: A sampling means 1 samples data in a prescribed period. and stores the data in a buffer storage means 2. A required command such as K1, Kn, etc., is inputted from a command input means 4. An arithmetic processing means 3 receiving the command calls the data sampled in a period NS by the buffer storage means 2, and performs prescribed arithmetic processing in a period shown in equation, and stores the result of arithmetic processing in a storage means 5 with sampled data. When a desired computed result is inputted from the command input means so as to be displaied, the arithmetic means 3 calls a commanded computed result from the storage means 5, and displays the content of the result on a display means 6. K1, Kn and (n) in equation represent integers ≥2.