filling an array..

Hi,
I've got this homework:
Write a program that calculates the Root-Mean-Square (RMS) of a
sequence of numbers whose length and content are determined by the
user. The RMS calculation should be done in a function of prototype
double RMS(double *x, int N), where N is the number of elements
in the array x. Demonstrate its use in a main function which prompts
the user for the length of the sequence, and then the values of this
sequence.

And I've got that far:

Code:

#include <stdio.h>
#include <math.h>


double RMS(double *x, int N)
{
   float rms;
   int i;
   for (i=0; i<N; i++) {
   rms=sqrt(x[N^2]);
}
    
   return rms;
}


int main()
{
   int i, N;
   float rms;
   printf("Please enter the length of the sequence:\n");
   scanf("%d", &N);
   double x[N];
   for (i=0;i<N;i++){
   printf("Please enter the values:\n", i+1);
   scanf("%d", &x[N]);
}
   rms=RMS(x,N);
   printf("%f", rms);
    
   return0;
}

It doesn't give me any errors but neither does it work.. Can someone please tell me if I'm on the right track?

Thanks

This is wrong; the "^" is NOT the power operator in C.
Look for pow or power in math library. http://www.cplusplus.com/reference/clibrary/cmath/pow/

Code:

rms=sqrt(x[N^2]);

Even if it was right the equation is wrong.
http://en.wikipedia.org/wiki/Root_mean_square


Tim S.

Thanks for reply. Sorry if I'm a bit slow but I'm quite new to programming..
I changed the function but it still doesn't work.

Code:

#include <stdio.h>
#include <math.h>


double RMS(double *x, int N)
{
	float rms;
	int i;
	int y=2;
	int z=1;
	for (i=0; i<N; i++) {
		rms=sqrt((z*pow(*x,y))/N);
	}
	
	return rms;
}

Unfortunately I have no idea how to type it properly..

Originally Posted by kromagnon

Code:

	for (i=0; i<N; i++) {
		rms=sqrt((z*pow(*x,y))/N);
	}

How does the value of rms differ from being inside the for loop?
Hint: No matter how many times it runs in the for loop the answer is the same.

Your math is wrong. And, the value of *x does not change for each loop run.
http://upload.wikimedia.org/wikipedi...d9fd08e730.png

Hint2: create a function print_text that just displays the value in the array.
Once you get that to work, you will know more about writing RMS function.

Code:

void print_text(double *x, int N);

Tim S.