Patent ID: 7191204

Claim:
An operation system, wherein from the divisor in a division operation, the approximate value of a reciprocal of the divisor is acquired; the value is used as an initial value to carry out an iteration calculation of the Newton-Raphson method more than once to obtain the reciprocal of requisite accuracy; and the reciprocal is multiplied by a dividend for the division operation, characterized in that: the system is provided with a circuit dedicated for the iteration calculation of the Newton-Raphson method and the initial value in the calculation is rounded to a value of minimum accuracy necessary for the calculation to make subordinate bits of the rounded value zero, so that a part of a multiplication circuit used for the iteration calculation is abbreviated; and a formula of the iteration calculation of the Newton-Raphson method is modified to separate a difference and partial products related to bits in which 0 or 1 is continued from the most significant bit (MSB) of the difference are eliminated in the multiplication circuit under utilization of the fact that an absolute value of the difference is small.