shiyan1.c

牛顿法计算方程,可以计算非线性方程/方程组,有需要的可以试试,主要是数学方法的实现

#include<stdio.h> 
#include<math.h> 
#include<conio.h> 
float f1(float x1,float x2) 
{ 
return 2*x1+x1*x2-3.3; 
} 
float f2(float x1,float x2) 
{ 
return 2*x2-x1*x2-0.9; 
} 
float fd1(float x1,float x2) 
{ 
return 2+x2; 
} 
float fd2(float x1,float x2) 
{ 
return x1; 
} 
float fd3(float x1,float x2) 
{ 
return -x2; 
} 
float fd4(float x1,float x2) 
{ 
return 2-x1; 
} 
float f3(float x1,float x2) 
{ 
return 1/((2+x2)*(2-x1)+x1*x2); 
}
int main(void) 
{ 
float x3=1.0,x4=0.9,x1=1.0,x2=0.9; 

do
{ 
x3=x1;
x4=x1; 
x1=x3-f3(x3,x4)*(fd4(x3,x4)*f1(x3,x4)-fd3(x3,x4)*f2(x3,x4));//迭代公式求近似根；
x2=x4-f3(x3,x4)*(fd2(x3,x4)*f1(x3,x4)+fd1(x3,x4)*f2(x3,x4)); 
}while((fabs(x1-x3)>1e-6)&(fabs(x2-x4)>1e-6)); 
printf("x1=%f\n",x1); 
printf("x2=%f\n",x2);
getch(); 
return 0; 

/*释放内存空间*/

free(x1);

free(x2);

free(x3);

free(x4);

}