PURPOSE: To conduct the processing of obtaining an autocorrelation function of array data subjected to arithmetic operation processing at a high speed with a less step number by writing array data subjected to arithmetic operation processing to 1st and 2nd storage means simultaneously by a write means.

CONSTITUTION: Array data stored in a memory 1 are read and shifted left by a barrel shifter 7 and stored tentatively in a latch circuit 10 via a register 9 and a bus 3. While a write control section 11 outputs a write signal 12 of the memory 1 and a write signal 13 of a memory 2, the section 11 commands write of an output of the latch circuit 10 to the memories 1, 2 to store the array data after scaling processing to both the memories 1, 2 simultaneously. Then the array data are read simultaneously from the memories 1, 2 and product sum is calculated by using a multiplier 5, an ALU 8 and a register 9. Thus, the processing of transferring the array data after scaling processing from the memory 1 to the memory 2 is not required.