bestfitcircle.c:46: error: called object is not a function

That is the error message that I get for the following C program.

Code:#include <stdio.h> #include <math.h> main() { int count, points, x_sum = 0, y_sum = 0; float x_avg, y_avg, sigma[7], k_prime, h_prime, h, k, r = 0; for(count = 0; count < 7; count++){ sigma[count] = 0; } printf("How many points?\n"); scanf("%d", &points); float x[points], y[points], x_prime[points], y_prime[points]; for(count = 0; count < points; count++){ printf("Insert x of point #%d:\n", count+1); scanf("%f", &x[count]); printf("Insert y of point #%d:\n", count+1); scanf("%f", &y[count]); } for(count = 0; count < points; count++){ x_sum = x_sum + x[count]; y_sum = y_sum + y[count]; } x_avg = x_sum / points; y_avg = y_sum / points; for(count = 0; count < points; count++){ x_prime[count] = x[count] - x_avg; y_prime[count] = y[count] - y_avg; } for(count = 0; count < points; count++){ sigma[0] = sigma[0] + pow(x_prime[count],2); sigma[1] = sigma[1] + (x_prime[count] * y_prime[count]); sigma[2] = sigma[2] + pow(x_prime[count],3); sigma[3] = sigma[3] + (x_prime[count] * pow(y_prime[count],2)); sigma[4] = sigma[4] + pow(y_prime[count],2); sigma[5] = sigma[5] + (y_prime[count] * pow(x_prime[count],2)); sigma[6] = sigma[6] + pow(y_prime[count],3); } k_prime = ((sigma[0] * (sigma[5] + sigma[6])) + (sigma[1] * (sigma[2] + sigma[3]))) / (2 * ((sigma[4] * sigma[0]) - (sigma[1] * sigma[1]))); h_prime = (((1 / 2)(sigma[2] + sigma[3])) - (k_prime * sigma[1])) / sigma[0]; k = k_prime + y_avg; h = h_prime + x_avg; for(count = 0; count < points; count++){ r = r + sqrt(pow(x_prime[count]-h,2) + pow(y_prime[count]-k,2)); } r = r / points; printf("Best-fit circle center is: %f, %f\nBest-fit circle radius is: %f\n", h, k, r); }

I have not a clue what the problem is.