Compute Spline

Description

Splines are smooth polynomial functions that are used in Dendro Tools to enhance the variability within an input time series. This tool computes n-year cubic smoothing splines and outputs the original values and all splines to the output file specified by the user. A plot is also generated for visual inspection (see "Plotted Data" under "Output Spline" below).

Input Data

File
Select the input data to analyze by clicking on "Browse" and navigating to the proper file.

Input Data Format
Year / Data

Each "/" is a tab (i.e., data should be tab-delimited). Missing Data should be denoted as "-99".

Start Row
This input is the row number where the main data to be processed begin in the input file selected above. An example of how row numbers are entered is shown in Figure 2 located in the Running Dendro Tools topic.

Column Number
This input is the column number where the data are located in the input file selected above. An example of how column numbers are entered is shown in Figure 2 located in the Running Dendro Tools topic.

Event Years
Enter the n-year splines one line at a time (e.g., enter 10, hit return, enter 20, hit return, and enter 30 to create 10-, 20-, and 30-year cubic smoothing splines).

Output Data

File
Select or enter the name of the file where the results will be stored.

Header
Information entered here will be output in the first line of the output file.

Output Spline

Plotted Data
Once the compute spline tool has been run, a plot will automatically be generated (Fig. 1). If more than one n-year spline was computed, then the other splines can be plotted by selecting the spline next to "Displayed Spline". Note also that splines have issues with edge effects. Thus, Dendro Tools automatically truncates the splines by 5 years at the start and end of the time series. The truncated data are still available in the output file and can be displayed in the plot by unchecking "Truncate Spline (Limit Edge Effects)".

Figure 1. A 10-year cubic smoothing spline has been computed for the November-May reconstruction at Mesa Verde (black line). The red line denotes the November-May Mesa Verde reconstruction that was input to compute the spline.