Not passing array correctly to function

Projects Programming
3 
  leastSqrRegression(*Collection, 6);

This is a big red flag. Re-write the function so you can just pass it Collection.

void loop() {
  leastSqrRegression(*Collection, 6);
  while (1);
}

If you only want to call the function once, why are you calling it in loop()? Call it in setup() instead, and leave loop() empty.