public abstract class Calculate {
public Calculate(){
}
public abstract double function(double x);
public abstract double function(double x,double y);
/**
* 牛頓-萊布尼茲積分
* */
public double Integral(double x1,double x2,double eps){
if(x2==x1){
try {
throw new Exception("很差意思，貌似不能夠這麼積分");
} catch (Exception e) {
e.printStackTrace();
}
}
double length=Math.abs(x1-x2);
int n=(int)(1/eps);
double steps=length/n;
double sum=0;
for(int i=0;i<n;i++){
double height=function(x1+steps*i);
double square=steps*height;
sum=sum+square;
}
return sum;
}
public double Integral(double x1,double x2,double y1,double y2,double eps){
double lengthY=Math.abs(y2-y1);
double lengthX=Math.abs(x2-x1);
int n=(int)(1/eps);
double stepsY=lengthY/n;
double stepsX=lengthX/n;
double sum=0;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
double heightY=function(x1+stepsX*i,y1+stepsY*j);
double squareY=heightY*stepsY*stepsX;
sum=sum+squareY;
}
}
return sum;
}
}
public class test{
public static void main(String[] args){
class C extends Calculate{
@Override
public double function(double x) {
// TODO Auto-generated method stub
return x;
}
@Override
public double function(double x, double y) {
return E.e(x)*E.e(y);
}
}
C c=new C();
double r=c.Integral(0, 1,0,1,0.00005);
System.out.println((E.e(1)-1)*(E.e(1)-1));
System.out.println(r);
}
}