如何用 apache common math 3.3 计算积分答案

【问题标题】：how to calculate integral with apache common math 3.3如何用 apache common math 3.3 计算积分
【发布时间】：2014-05-27 08:20:19
【问题描述】：

我想用 apache commonmath3.3 lib 计算一些实验的积分。

我看到this question.

SimpsonIntegrator simpson = new SimpsonIntegrator();
TrapezoidIntegrator trapezoid = new TrapezoidIntegrator();
double[] vector = new double[2];
vector[0] = 0;
vector[1] = 1;

PolynomialFunction f = new PolynomialFunction(vector);
UnivariateFunction uf = (UnivariateFunction)new PolynomialFunction(vector);
System.out.println("To String " + uf.toString());
System.out.println("Degree: " + f.degree());

double i = simpson.integrate(10, uf, -Float.MAX_VALUE, Float.MAX_VALUE);
double j = trapezoid.integrate(10, uf, 0, 1);
System.out.println("Simpson integral : " + i);        
System.out.println("Trapezoid integral : " + j);

我认为我们必须为整数的间隔创建一个双数组。但是当我想创建大小超过 2 的数组时，我会给出以下信息：

Caused by:org.apache.commons.math3.exception.TooManyEvaluationsException: illegal state: maximal        count (10) exceeded: evaluations 05-27 08:11:33.461: E/AndroidRuntime(1349):    at     org.apache.commons.math3.analysis.integration.BaseAbstractUnivariateIntegrator.computeObjec tiveValue(BaseAbstractUnivariateIntegrator.java:218)

我错过了什么吗？

如何声明积分函数？
例如，我如何为积分声明“x^2+3”函数？

【问题讨论】：

标签： java integral apache-commons-math

【解决方案1】：

在更复杂的多项式函数的情况下，您需要创建积分器允许的最大评估次数。

试试这样的：

SimpsonIntegrator simpson = new SimpsonIntegrator();
TrapezoidIntegrator trapezoid = new TrapezoidIntegrator();
double[] vector = new double[3];
vector[0] = 0;
vector[1] = 1;
vector[2] = 2;

PolynomialFunction f = new PolynomialFunction(vector);
UnivariateFunction uf = (UnivariateFunction)new PolynomialFunction(vector);

double i = simpson.integrate(10, uf, -Float.MAX_VALUE, Float.MAX_VALUE);
double j = trapezoid.integrate(10000, uf, 0, 1);
System.out.println("Simpson integral : " + i);        
System.out.println("Trapezoid integral : " + j);

【讨论】：