java 线性插值

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在离散数据的基础上补插连续函数，使得这条连续曲线通过全部给定的离散数据点。插值是离散函数逼近的重要方法，利用它可通过函数在有限个点处的取值状况，估算出函数在其他点处的近似值。

引入maven

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<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-math3</artifactId>
    <version>3.6.1</version>
</dependency>

完整代码

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 public static double[] interpolations(double[] x, double[] y, double[] z) {
   double[] interV = new double[z.length];
   UnivariateInterpolator interpolator = new LinearInterpolator();
//UnivariateInterpolator interpolator = new SplineInterpolator();平滑曲线
   UnivariateFunction function = interpolator.interpolate(x, y);
   for (int i = 0; i < z.length; i++) {
     interV[i] = function.value(z[i]);
   }
   return interV;
 }

 public static void main(String[] args) {
   //已知下标1,3,5,7,9对应的数值为0.1, 0.5, 2.2, 1.2, 3.1，求下标2, 4, 6, 8对应的数值
   double[] x = new double[] {1, 3, 5, 7, 9};
   double[] y = new double[] {0.1, 0.5, 2.2, 1.2, 3.1};
   double[] z = new double[] {2, 4, 6, 8};
   double[] v = interpolations(x, y, z);
   System.out.println(Arrays.toString(v));
 }

common-math3官方文档