Wu Jinming, Liu Yuanyuan, Zhang Xiaolei. Quadratic spline interpolation from the integral values of successive subintervals[J]. Journal of Image and Graphics, 2016, 21(4): 520-526. DOI: 10.11834/jig.20160414.
the integral values of several subintervals are known
whereas the usual function values at the knots are not given. In this article
we propose an integro quadratic spline interpolation method from the integral values of successive subintervals. First
we use the linear combination of quadratic B-spline functions to satisfy the given integral values and two additional boundary conditions. This problem is equivalent to solving a system of +2 linear equations with a three-band coefficient matrix. Second
we use operator theory to conduct an error analysis and obtain the super convergence order in approximating the function values at the knots. Lastly
we deal with the integro interpolation problem even without any boundary condition based on the linear combination of integral values to approximate the boundary function values. The proposed and modified methods are tested by functions with low frequency in Example 1; the approximation behavior are satisfactory. Meanwhile
the proposed method is tested by functions with high frequency in Example 2; the numerical convergence order is consistent with the theoretical value. The proposed method is easier to implement than other existing methods. The super convergence in approximating function values at the knots is also verified. The proposed method of function reconstruction from the integral values of successive subintervals is universally applicable.