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83 lines
3.5 KiB
83 lines
3.5 KiB
\chapter{Informational and Error Messages} \label{chap:errmsg}
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\caps{\PROGRAM} operates in three stages:
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\begin{enumerate}
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\item scan the input database for general information,
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\item input commands and equations from the user,
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\item re-read the input database and copies the mesh description to
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the output database, and
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\item evaluate the equations for each time step.
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\end{enumerate}
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\caps{\PROGRAM} expects a valid database. If a format error is
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discovered before the time steps, the program prints an error of the
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following format:
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\errfmt{
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\cmd{DATABASE ERROR - Reading \param{database item}}
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}
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and aborts. This problem may occur either while scanning the input
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database or while copying the mesh description to the output database.
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If a format error is found while reading the time steps, the following
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error message is printed:
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\errfmt{
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\cmd{WARNING - End-of-file during time steps} \\
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or \\
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\cmd{DATABASE ERROR - Reading \param{database item}}.
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}
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If this error is encountered while scanning the input database, the time
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step with the error and all following time steps are ignored, but the
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program continues and the previous time steps are available for
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processing. Some database errors may not be detected until the equations
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are being evaluated. The program aborts when the error is encountered,
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but the output database is correct for all previous time steps.
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An equation is checked for syntax errors as soon as the user enters the
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line. If an error is found, a message is printed and the equation is
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ignored (with a message to that effect). If only a warning is printed,
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the equation is accepted. If the message is not sufficiently
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informative, the description of the equation syntax
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(Chapter~\ref{chap:equation}) may be helpful.
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A command is performed as soon as it is entered. A command error usually
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causes the command to be ignored. The command is usually performed if
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only a warning is printed. The display after the command shows the
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effect of the command. If the message is not sufficiently informative,
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the appropriate command description (Chapter~\ref{chap:command}) may be
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helpful.
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The evaluation loop processes each time step by reading the needed input
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database variables, evaluating the equations, and writing the results to
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the output database. Any error during this stage causes the program to
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abort (with a fatal error message). The output database is readable, but
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it contains only the data from the time steps processed before the
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error.
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A numerical error while evaluating the equations (such as divide by
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zero) causes a fatal error. A message is printed describing the error
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and the equation that caused the error is displayed after the error
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message.
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The program allocates memory dynamically as it is needed. If the system
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runs out of memory, the following message is printed:
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\errfmt{
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\cmd{FATAL ERROR - Too much dynamic memory requested}
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}
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and the program aborts. The user should first try to obtain more memory
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on the system. Another solution is to run the program in a less
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memory-intensive fashion. For example, entering fewer equations may
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require less memory.
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\caps{\PROGRAM} has certain programmer-defined limitations (for example,
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the number of curves that may be defined. The limits are not specified
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in this manual since they may change. In most cases the limits are
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chosen to be more than adequate. If the user exceeds a limit, a message
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is printed. If the user feels the limit is too restrictive, the code
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sponsor should be notified so the limit may be raised in future releases
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of \caps{\PROGRAM}.
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