aaa.rar_求极值 C

#include "stdio.h" //返回3*3行列式的值 double Determinant(double a11,double a12,double a13, double a21,double a22,double a23, double a31,double a32,double a33) { return a11*(a22*a33-a23*a32)-a12*(a21*a33-a23*a31)+a13*(a21*a32-a31*a22); } //函数将data[]数组中的n个数用最小二乘法拟合成y = a*x*x+b*x+c //a,b,c分别为二次项,一次项,常数项的系数 //函数调用成功返回 1 int Fitting(double* DataX,double* DataY,int Num,double* a,double* b,double* c) { double x1,x2,x3,x4,right1,right2,right3; double Denominator,aMolecular,bMolecular,cMolecular; x1 = x2 = x3 = x4 = right1 = right2 = right3 = 0; int loop; for(loop = 0 ; loop < Num ; loop++) { x1 += DataX[loop]; x2 += DataX[loop]*DataX[loop]; x3 += DataX[loop]*DataX[loop]*DataX[loop]; x4 += DataX[loop]*DataX[loop]*DataX[loop]*DataX[loop]; right1 += DataX[loop]*DataX[loop]*DataY[loop]; right2 += DataX[loop]*DataY[loop]; right3 += DataY[loop]; } Denominator = Determinant(x4,x3,x2,x3,x2,x1,x2,x1,Num); if(Denominator==0) return 0; aMolecular = Determinant(right1,x3,x2,right2,x2,x1,right3,x1,Num); bMolecular = Determinant(x4,right1,x2,x3,right2,x1,x2,right3,Num); cMolecular = Determinant(x4,x3,right1,x3,x2,right2,x2,x1,right3); *a = aMolecular / Denominator; *b = bMolecular / Denominator; *c = cMolecular / Denominator; return 1; } //测试 int main() { double x[4] = {3,4,6,9}; double y[4] = {10,20,33,44}; double a,b,c; Fitting(x,y,4,&a,&b,&c); printf("%lf %lf %lf",a,b,c); return 0; }