Question

A polynomial P is a function defined by an array of coefficients CI. Example : C-(4, 2, 1), then In the general case, given the array CI of size N, we can define Write a program - with the function main0 that gets N, the coefficients C] and a value x from the user. - with a function poly( that calculates and returns the value of P(x). The arguments of the function poly includes the value x, the coefficients C and N - with a function derivative() that calculates and returns the value of P'(x) (ie derivative of P at the point x). The arguments of the function derivative0 includes the value x, the coefficients C and N. In the main0 function, have your program call the functions poly0 and derivative0 to calculate numerically P(x) and P'(x). Output the numerical values of P(x) and P'(x)

*Please try to use C++ specific coding for my understanding because I never learned C.

Answer 1

//pls provide +ve rating, thanks

#include<iostream>

using namespace std;

int poly(int x, int coe[], int n);
int derivative(int x, int coe[], int n);

int main()
{
   int n;
   cout << "Enter number of terms: ";
   cin >> n;
   int *coe;
   //allocate memory for n number of elements
   coe = new int[n];
  
   for (int i = 0; i < n; i++)
   {
       cout << "coefficients " << i << ": ";
       cin >> coe[i];
   }
   int x;
   cout << "Enter the value of x: ";
   cin >> x;
  
   cout << "P(x): " << poly(x, coe, n) << endl;;
   cout << "P'(x): " << derivative(x, coe, n);
}

int poly(int x, int coe[], int n)
{
   int sum = 0;
   for (int i = 0; i < n; i++)
   {
       sum += coe[i] * pow(x, i);
   }
   return sum;
}
int derivative(int x, int coe[], int n)
{
   int sum = 0;
   for (int i = n - 1; i > 0; i--)
   {
       sum += i * coe[i] * pow(x, i - 1);
   }
   return sum;
}

=====================================

/*Output1
Enter number of terms: 3
coefficients 0: 4
coefficients 1: 2
coefficients 2: 1
Enter the value of x: 2
P(x): 12
P'(x): 6
//output2
Enter number of terms: 4
coefficients 0: 89
coefficients 1: 6
coefficients 2: 4
coefficients 3: 3
Enter the value of x: 2
P(x): 141
P'(x): 58
*/