linear regression for advanse

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

float mean(float *x, int n);
float summation(float *x, int n);
float summation2(float *x, float *y, int n);
void estimate(float intercept, float slope);
int getN();

int main() {
    int n = getN(); //number of programs
    float x[n] = 0; //estimated LOC for program n
    float y[n] = 0; //actual LOC for program n

    float sumX = 0;
    float sumY = 0;
    float sumXX = 0;
    float sumXY = 0;

    float slope = 0;
    float intercept = 0;

    //get the x and y
    int i = 0;
    for(i=0; i<n; i++) {
        printf("Input estimated LOC for program %d: ", i+1);
        scanf("%f", x[i]);
        printf("Input actual LOC for program %d: ", i+1);
        scanf("%f", y[i]);
    }

    //calculation

    //summation(x, n);

    /* calculate summations (summation)
     * calculate x*y summations (summation2)
    */

    slope = ((n*sumXY) - (sumX*sumY)) / ((n*sumXX)-(sumX*sumX));

    intercept = ((sumY - (slope*sumX)) / n);

    printf("Regression equation is:\n  y = %f +%fx", intercept, slope);

    //ask user for programs to estimate
    //make a new function for that
    //continue to work until user types exit

    printf("Exiting program. Press any key to continue.");
    getch();
}



float mean(float *x, int n) {
    float result = 0;
    int i = 0;
    for(i=0; i<n; i++) {
        result = result + x[i]
    }
    result = result/n;
    return result;
}

float summation(float *x, int n) {
    float result = 0;
    int i = 0;
    for(i=0; i<n; i++) {
        result = result + x[i];
    }
    return result;
}

float summation2(float *x, float *y, int n){
    float result = 0;
    int i = 0;
    for(i=0; i<n; i++) {
        result = result + x[i]*y[i];
    }
    return result;
}

float estimate(float intercept, float slope) {
    int exit = 0;

    while() {
        printf("");
        //compute
    }
}

int getN() {
    int x = 0;
    printf("Input number of programs: ");
    scanf("%d", &x);
    return x;
}