• Revised Computer Programs for Tree-Ring Research

      Graybill, Donald A.; Laboratory of Tree-Ring Research, The University of Arizona (Tree-Ring Society, 1979)
      Three computer programs that are basic to the processing and development of tree -ring chronologies are now available. They were designed to refine and replace older programs that were previously furnished by the laboratory. Program RWLIST replaces program RWLST and is used for data inspection. Programs INDEX and SUMAC replace INDXA. INDEX is used for curve fitting procedures while SUMAC does summaries of series of indices, analysis of variance and cross-correlation. The new programs represent an increase in efficiency and flexibility in use. They are written in current ANSI Fortran IV and will be readily adaptable to most computing environments.
    • Tree-Ring Skeleton Plotting by Computer

      Cropper, John Philip; Laboratory of Tree-Ring Research, The University of Arizona (Tree-Ring Society, 1979)
      Skeleton plotting is an established manual technique for representing the relative narrowness of tree rings in a single radius. These plots can be used as a visual aid to crossdating. This paper describes a method for deriving these plots by computer. The method uses a low-pass digital filter, running means, and standard deviations of ring-width measurements. When the manual and computer plots are compared for the same series, approximately 85% agreement is found. Examples of results are presented for specimens from sensitive, moderate, and complacent sites. FORTRAN program listings are included for two subroutines for (a) identifying small rings and (b) producing the plot.