A
secret share value [ft(x)−f′t(x)] of ft(x)−f′t(x) is obtained through secure computation using a
secret share value [x] of a real number x, and a
secret share value [ft(x)−f′t(x)]r of (ft(x)−f′t(x))r obtained by right-shifting ft(x)−f′t(x) by the predetermined number of bits is obtained through secure computation using the secret share value [ft(x)−f′t(x)]. Here, [μ] is a secret share value of μ, n is an integer equal to or greater than 1, t=0, . . . , n−1, u=1, . . . , n−1, ft(x) is a function of the real number x, f′t(x) is an
approximation function of the function ft(x), a secret share value [f′0(x)] of an
approximation function f′0(x) is [f′0(x)]=c0,0+c0,1[x], a secret share value [f′u(x)] of an
approximation function f′u(x) is [f′u(x)]=cu,0+cu,1[x]+cu,2[f0(x)]+ . . . +cu,u+1[fu−1(x)], ct,0 is a public value, and ct,1, . . . , ct,n+1 are coefficients.