LINEST_SEM() returns the
aggregated standard error of the m value of a linear regression defined
by the equation y=mx+b for a series of coordinates represented by paired numbers given by the expressions x_value and y_value, iterated over the chart
dimensions.
linest_sem([{set_expression}][ distinct ] [total [<fld {,fld}>] ] y-expression,
x-expression [, y0 [, x0 ]] )