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Gyst is a generalized growth and yield
shell developed for the Windows operating system by the Loblolly Pine
Growth and Yield Research Cooperative at Virginia Tech. The purpose
of GYST is to provide developers and users of growth and yield models
with a readily available interface for implementation of different kinds
of models. Users do not need to write tedious user interface code for
each new application. Nor are they restricted to accessing one or a
few models imbedded in executable code. Instead, users can access growth
and yield models by selecting them from a library of models. Models
can be added or deleted from the libraries and there are no restrictions
placed on how the models have been developed, order of execution within
the models, or number, type, and names of variables. Thus, users can
insert their own existing growth and yield models as either C or FORTRAN
dynamic linked libraries, (DLLs) into the shell for implementation.
GYST is useful for a variety of purposes including assessing the performance
of alternative models, inventory updating, testing newly developed growth
and yield models and archiving and accessing models.
How GYST works
GYST works by linking data to growth and
yield models within a spreadsheet environment. Columns are variables
passed into and out of DLLs that have been developed and are archived
in the library of models. Data (stand- or tree-level variables) are
inserted into the cells of the spreadsheet either manually or read in
as a delimited ASCII file. Buttons from the toolbar (such as "Initialize"
or "Grow") activate the link between the data and models causing
the data to be passed into the models for computation and back out to
the spreadsheet.
GYST in a Windows application
GYST has the same basic functionality
as other Widows Applications. File functionality includes importing
and exporting data, opening and using multiple GYST windows and saving
GYST projects. Edit capability includes Windows clipboard access which
allows integration with other Windows applications such as graphics
packages and word processors. Spreadsheet functionality includes block
highlighting, sorting, printing and moving about the cells of the spreadsheet.
What GYST does
GYST can initialize a current stand, grow
a stand, or display a stand table. Initializing a stand passes stand
variables to the stand-level portion of the DLL for prediction of current
conditions. Growing a stand projects stand attributes into the future
using the specified stand-level growth algorithm in the DLL. Growth
can be accomplished for a desired number of years or to a specified
target value of on of the column variables. Output can be obtained at
specific intervals. Projections can be made to minimum or maximum values
of specified variables. A stand/stock table can be created by passing
stand-level variables to the selected stand/stock table portion of the
DLL.
Download a Demonstration Version
To download a demonstration version:
1. Click GYST to start downloading.
2. With your web browser select "save this program to disk".
3. Run the file saved in step 2 by double clicking it. The setup
utility starts.
4. Run the demo program in the destination directory of step 3.
GYST is available for $295. To place an order or obtain additional
information, contact ralph@vt.edu
.
GYST user manual
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