C语言有趣的数组指针

使用三个数组。第三个数组的元素用EXTEND的含指针函数计算而得，报错为cannot convert parameter 1 from 'double [10]' to 'double'
小弟求解！望解释




#include<stdio.h>
void extend(double , double ,double );

int main()
{
double price[]={10.62,14.89,13.21,16.55,19.62,9.47,6.58,19.32,12.15,3.99};
double quantity[]={4,9.5,6,7.35,9,15.3,3,5.4,2.9,4.9};
double amount[10];
int j;


extend(price,quantity,amount);

for(j=0;j<10;j++)
printf("the element %d is %f\n",j,amount[j]);
return 0;
}
void extend(double *p, double *q,double *a)
{
int i;
for(i=0;i<10;i++)
*(a+i)=*(p+i)+*(q+i);

}