Cubic equation calculation apparatus and cubic curve coordinate data generation apparatus using the same

摘要

A cubic equation calculation apparatus calculates f(n) of a function when a cubic equation variable T=n is defined by f(T)=AT.sup.3 + BT.sup.2 + CT+D where A, B, C and D are constants. The apparatus includes a first calculation circuit using a process where variable T is incremented by 1 from 1, for calculating coefficient data A.sub.n, B.sub. n, C.sub.n and D. sub.n when T=n (n=1, 2, . . . ) in accordance with A. sub.n =A.sub.n-1 ; B. sub.n =3A.sub.n-1 +B.sub.n-1 ; C.sub.n =3A.sub.n-1 + 2B.sub.n-1 +C.sub.n-1 ; D.sub.n =A.sub.n-1 +B.sub.n-1 +C.sub.n-1 +D.sub.n- 1 ; and using coefficient data A.sub.1, B.sub.1, C.sub.1 and D.sub.1 when T=1 being such that A.sub.1 =A, B.sub.1 =B, C.sub.1 =C and D.sub.1 =D, and using coefficient data A.sub.n-1, B.sub.n-1, C.sub.n-1 and D.sub.n-1 when T=n-1. The apparatus also includes a second calculation circuit for calculating f(n) in accordance with f(n)=A.sub.n +B.sub.n +C.sub.n +D.sub. n when T=n. A cubic curve coordinate data generation apparatus is provided, using the cubic equation calculation apparatus.