Patent ID: 7447724

Claim:
An error function calculation device which performs processing of calculating an error function F M (T) defined by the following equation (1) and having T (positive real number) as a variable, t (0 to 1) as a function variable, and M (M is an integer of 0 or more) as an order, F M ⁡ ( T ) = ∫ 0 1 ⁢ t 2 ⁢ M ⁢ exp ⁡ ( - Tt 2 ) ⁢ ⁢ ⅆ t ( 1 ) the error function calculation device comprising: a coefficient table which stores a value of F M+i (T 0 )/F M (T 0 ) (i is at least one integer among 1 to n, and n is a natural number) calculated for a predetermined T 0 , obtained by an n-th order polynomial approximation of the error function F M (T), or a value obtained by multiplying the value of F M+i (T 0 )/F M (T 0 ) by a constant; and a calculation section which reads the value of F M+i (T 0 )/F M (T 0 ) or the value obtained by multiplying the value of F M+i (T 0 )/F M (T 0 ) by a constant from the coefficient table, and performs at least a part of the processing of calculating a value of the error function F M (T) by a fixed-point arithmetic using the value of F M+i (T 0 )/F M (T 0 ) or the value obtained by multiplying the value of F M+i (T 0 )/F M (T 0 ) by a constant.