I need some help with C++ please. I\'m supposed to write a program that calculat
ID: 3570284 • Letter: I
Question
I need some help with C++ please. I'm supposed to write a program that calculates the derivative of a function at a given point. This is to be done with the most basic of differentiation rules, which is the power rule. If you're unfamiliar, the power rule says that you take a function, for example f(x)=6x^3, and multiply the exponent by the leading coefficient, then lower the exponent by 1. So for the example, the derivative f'(x)=18x^2. This then needs to be evaluated at any user entered point for x.
Explanation / Answer
/*
x: value of x in the polynomial
c: array of coefficients
n: number of coefficients
*/
double derivePolynomial(double x, double c[], int n) {
double result = 0;
double p = 1;
int counter = 1;
for(int i=n-1; i>=0; i--) //backward loop
{
result = result + c[i]*p*counter;
counter++; // number of power
p = p*x;
}
return result;
}
//Output in main() looks like this
double x=1.5;
double coeffs[4]={3,2.2,-1,0.5};
int numCoeffs=4;
cout << " = " << derivePolynomial(x,coeffs,numCoeffs) << endl;