Code:
#include "math.h"
#include "conio.h"
#include "iostream.h"
/*Nhap vao mot da thuc luu he so trong A[] va co Bac*/
double*NhapDaThuc(int Bac) {
double *A = new double [Bac+1];
for(int i= 0; i<=Bac; i++) {
cout<<"a"<<i<<" = ";
cin>>A[i];
}
return A;
}
/*Xuat da thuc co he so A[] va Bac*/
void XuatDaThuc( double*A,int Bac, char*s) {
cout<<"Da Thuc Vua Nhap la:\n";
cout<<s<<" = "<<A[0];
for(int i=1; i<=Bac; i++){
if(A[i]>0)
cout<<" + "<<A[i]<<"x^"<<i;
if(A[i]<0)
cout<<A[i]<<"x^"<<i;
}
}
/*Tinh gia tri cua da thuc tai diem x*/
double f(double*A, int Bac, double x) {
double KetQua = A[Bac];
for(int i=Bac-1; i>=0; i--)
KetQua=KetQua*x + A[i];
return KetQua;
}
/*Công thức Simpson tính tích phân .*/
double CongThucSimpson(double*A,int Bac, double a, double b, int n) {
double h = (b-a)/(2*n);
double TongFChan=0,TongFLe=0;
double*F = new double [2*n+1];
double KetQua;
for(int i=0; i<=2*n; i++)
F[i]=f(A,Bac,a+i*h);
for(i = 1;i<2*n;i++) {
if(i%2==0)
TongFChan+=F[i];
else
TongFLe+=F[i];
}
KetQua = (h/3)*(F[0]+F[2*n]+2*TongFChan+4*TongFLe);
delete F;
return KetQua;
}
/*Công thức Simpson tính tích phân , với f(x) là đa thức bậc Bacf, g(x) là đa thức bậc Bacg*/
double CongThucSimpson( double*Fx,int BacFx, double*Gx,
int BacGx, double a, double b, int n) {
double h = (b-a)/(2*n);
double TongFChan=0,TongFLe=0;
double*F = new double [2*n+1];
double KetQua;
for(int i=0; i<=2*n; i++) {
if (f(Gx,BacGx,a+i*h) == 0) {
cout<<"\nHam f(x)/g(x) khong lien tuc tren [a,b]";
return -1;
}
else {
F[i]=f(Fx,BacFx,a+i*h)/f(Gx,BacGx,a+i*h);
}
}
for(i = 1;i<2*n;i++) {
if(i%2==0)
TongFChan+=F[i];
else
TongFLe+=F[i];
}
KetQua = (h/3)*(F[0]+F[2*n]+2*TongFChan+4*TongFLe);
delete F;
return KetQua;
}
/*Chuong Trinh Chinh*/
void main() {
clrscr();
double*Fx,a,b,Epxilon;
int Bacf,n;
cout<<"Nhap Vao Bac Cua Da Thuc:";
cin>>Bacf;
Fx = NhapDaThuc(Bacf);
XuatDaThuc(Fx,Bacf,"f(x)");
cout<<"\nNhap Can Tich Phan a Den b:\n";
cout<<"a = ";
cin>>a;
cout<<"b = ";
cin>>b;
cout<<"Nhap Vao So Doan Chia n = ";
cin>>n;
cout<<"I = "<<CongThucSimpson(Fx,Bacf,a,b,n);
getch();
delete Fx;
}