Logarithm operation circuit device

摘要

PURPOSE:To reduce the error between an arithmetic value using a logarithm transformation expression and the integer data of the logarithmic arithmetic value by carrying the decimal fractions of the logarithmic arithmetic value or carrying or omitting in accordance with the value of the decimal fraction excluding the time when the first decimal fraction is '0', and operating the integer data of the logarithmic arithmetic value. CONSTITUTION:A first arithmetic circuit executes the logarithmic operation with the approximate expression of the polygonal line approximation for the data inputted. Thereafter, a second arithmetic circuit carries the decimal fractions of the logarithmic arithmetic value outputted from the first arithmetic circuit or carries or omits the decimal fractions in accordance with the value of the decimal fractions of the logarithmic arithmetic value excluding the time when the first decimal fractions of the logarithmic arithmetic value are '0' and the integer data of the logarithmic arithmetic value are operated. Thus, the error between the arithmetic value using the logarithmic converting expression and the integer data of the logarithmic arithmetic value can be reduced.