LINEST(y,x,affine,stats)
This function returns an array with the first row giving the regression coefficients for the independent variables x_m, x_(m-1),...,x_2, x_1 followed by the y-intercept if affine is true.
y: vector of values of dependent variable.
x: array of values of independent variables, defaults to a single vector 1,...,n.
affine: if true, the model contains a constant term, defaults to true.
stats: if true, some additional statistics is provided, defaults to false