Excel Trend function

Hi, does excel have an inbuilt function to evaluate a simple trend? In a worksheet each column represents a month, a=Jan, b=Feb, c=Mar, each row contains sales for the month. I'm hoping for a formula that I could enter in column d, the range being (A1:C1) and returns 0 for static trend, 1 for increase in trend, -1 for decrease in trend, or something similar. Does excel have a function that would do this. Thanks for any help.