Horner's Algorithm

[swanley007]

Hello,

I am a college student, and I got a question wrong on the last test. I was wondering if anyone could give me the answer, as I am stumped and frustrated.

HERE IT IS:

Horner's Algo can be used to evaluate a polynomial at a point O(n) time.

SEE ATTACHMENT (COULDN"T GET FORMATTING IN THIS WINDOW)
MANY SUPER AND SUBSCRPITS

[dwks]

(COULDN"T GET FORMATTING IN THIS WINDOW)

That's what [code] [/code] tags are for.

[dwks]

double routineC(double coeffs[], int size, double x) {
      int I;  // intended to be i?
      double y = 0;
      for(i=0;i<=size;i++){  // i is undeclared
	y += coeffs[i] * pow(x,i);
     }
}

[rockytriton]

might want to return y after the for loop too.

[dwks]

And come to think of it

for(i=0;i<=size;i++){

you probably want < there, since you're using it to access the array.

[swanley007]

You are correct with your changes, sorry I guess I typed too fast...But it still leaves the rest of the problem.

[dwks]

The rest of the problem? You mean the code that you haven't written yet?

[Rashakil Fol]

That's not Horner's algorithm. This is.

double horners(double * poly, int size, double x) {
	double ret = 0.0;

	double * end = poly + size;

	while (poly != end) {
		ret *= x;
		ret += *poly;
		++poly;
	}

	return ret;
}