csapp2e 家庭作业 5.20

double polyh2(double a[],double x,int degree)

{

long int i;

double x2=x*x;

double x3 =x2*x;

double result1,result2,result3 = a[degree];

for(i=degree-1;i>=9;i-=9)

{

result1 = result3*x3+ (a[i-2] + x*a[i-1] +x2*a[i]);

result2 = result1*x3+ (a[i-5] + x*a[i-4] +x2*a[i-3]);

result3 = result2*x3+ (a[i-8] + x*a[i-7] +x2*a[i-6]);

}

for(;i>=0;i--)

result3=a[i]+x*result3;

return result3;

}