using System;

namespace MembranePoreTester.Helpers
{
    public static class Interpolation
    {
        // 线性插值
        public static double Linear(double[] xs, double[] ys, double x)
        {
            if (xs.Length == 0 || ys.Length == 0 || xs.Length != ys.Length)
                throw new ArgumentException("数组长度不匹配或为空");

            if (x <= xs[0]) return ys[0];
            if (x >= xs[^1]) return ys[^1];

            int i = Array.BinarySearch(xs, x);
            if (i >= 0) return ys[i];

            i = ~i; // 大于 x 的第一个索引
            double x0 = xs[i - 1], x1 = xs[i];
            double y0 = ys[i - 1], y1 = ys[i];
            return y0 + (y1 - y0) * (x - x0) / (x1 - x0);
        }
    }
}