To calculate the linear trendline values, Excel offers the array function TREND () (see the notes above about array functions) that returns values along a linear trend: If the count of known_y's is different from known_x's, the INTERCEPT () and SLOPE () functions returns #N/A.If there is only one value in known_y's or known_x's, the INTERCEPT () and SLOPE () functions will return #DIV/0!.The SLOPE () function returns the slope (the parameter a) of a linear regression line based on known_y's and known_x's data: known_x's (required) are independent data values (see an example below) - a range or array of numeric values.known_y's (required) are dependent data values - a range or array of numeric values,.In other words, using the known_x's and known_y's data, it returns the value y of the function for x = 0: The INTERCEPT () function calculates the y value at which the linear trendline crosses the y-axis. Excel offers the following functions to calculate trendline parameters:
