yy = smooth(y,span,method) sets the span of method to span.For the loess and lowess methods, span is a percentage of the total number of data points, less than or equal to 1.For the moving average and Savitzky-Golay methods, span must be odd (an even span is automatically reduced by 1). yy = smooth(y,'sgolay',degree) uses the Savitzky-Golay method with polynomial degree specified by degree.