pass by reference

[preetii90]

hello everyone..i actually have a doubt in C programming but since this part of the code is similar to C++, im posting it here in this forum.
any form of help will be appreciated.

this is my code:

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


int main()
{
int i=0,a;
double points[100][1];
double s1, s2, s3, m1, m2;
double *sumX2=&s1, *sumY2=&s2, *sumXY=&s3, *meanX=&m1, *meanY=&m2;
double ObtainStatistics(double,int);
double trendLine(int);

FILE* fin=fopen("points.txt","r");

while(1)
{
fscanf(fin, "%lf %lf", &points[i][0],&points[i][1]);
if(feof(fin))
break;
i++;
}

fclose(fin);

for(a=0;a<i;a++)
printf("%lf %lf\n", points[a][0], points[a][1]);

printf("Value of n is: %d\n", i);

ObtainStatistics(points[i][1],i);


return 0;
}
double ObtainStatistics(double y[][],int x)
{
int b;

for(b=0;b<x;b++)
{
sumX2+= s;
sumY2+=y;
*sumXY+=(s*y);
*meanX= s1/x;
*meanY= s2/x;
}
}


but when i compile, there is this error coming out, reading, "undeclared identifier". this comes in the function called ObtainStatistics.
the variables, sumX2, sumY2, sumXY..and so on are giving me errors.

I am not sure why i get these errors since i have already declared these variables upfront.
if anyone knows what is wrong with my code, pls help
thanks

[bluezor]

The function definition is put after main. You need to let it know that there is such a function to use by putting the function name before main.
double ObtainStatistics, double y[][], int x);
(just put that before main and code what it does after main)

[preetii90]

hey!
thanks for the help, but the error still exists. I took the function, double ObtainStatistics, (double y[][], int x); and put it before main and left the rest of the code as it was.
Still, the compiler is no able to identify the variables,sumX2, sumY2, sumXY..and so on.

[bluezor]

Ah sorry... I misread the question. I don't really know C much but i'd pretty much guess that it's because the variables are only declared in main() and the function has no idea what they are.