LINEST function calculates the ``least squares'' line that best fit to your data in @known_y's. @known_x's contains the corresponding x's where y=mx+b.
If @known_x's is omitted, an array {1, 2, 3, ...} is used. LINEST returns an array having two columns and one row. The slope (m) of the regression line y=mx+b is given in the first column and the y-intercept (b) in the second.
If @known_y's and @known_x's have unequal number of data points, LINEST returns #NUM! error.