\chapter{Sample Session} \label{appx:example}

The following is an example session with \caps{\PROGRAM}. Text following
the \caps{\PROGRAM} prompt (\verb|ALG>|) is supplied by the user. The
program response (if any) is shown directly below the equation or
command. Comments on the example are in {\em italics}.

\newenvironment{comments} {\em}{}

\verb|ALG>| \cmd{LIST VARS}
\begin{verbatim}
Database:  /User/me/testing/input_databse.e

SAMPLE DATABASE FOR ALGEBRA

Number of coordinates per node       =     2
Number of nodes                      =   644
Number of elements                   =   480
Number of element blocks             =     1

Number of node sets                  =     0
Number of side sets                  =     0

Code:  MISCPROG  version  1.0       on  12/23/85  at  10:21:59
\end{verbatim}

\verb|ALG>| \cmd{LIST STEPS}
\begin{verbatim}
Number of time steps = 21
   Minimum time =  0.00
   Maximum time = 10.00
\end{verbatim}

\newpage
\verb|ALG>| \cmd{SHOW TMAX}
\vspace{-\medskipamount}
\begin{verbatim}
Select all times from 0.0 to 10.0
   Number of selected times = 21
\end{verbatim}
\verb|ALG>| \cmd{TMAX 5.0}
\vspace{-\medskipamount}
\begin{verbatim}
Select all times from 0.0 to 5.0
   Number of selected times = 11
\end{verbatim}
\verb|ALG>| \cmd{NINTV 5}
\vspace{-\medskipamount}
\begin{verbatim}
Select times 0.0 to 5.0 in 5 intervals with delta offset
   Number of selected times = 5
\end{verbatim}

\begin{comments}
These commands select up to 5 time steps between 0.0 and 5.0 starting at
an offset (1.0) from 0.0. The steps with the times nearest 1.0, 2.0,
3.0, 4.0, and 5.0 are selected. The equations are evaluated and the
results written to the output database only for the selected steps.
\end{comments}

\verb|ALG>| \cmd{LIST NAMES}
\begin{verbatim}
Coordinate names: R Z

Variables Names:
   Global:   RESIDUAL  ENERGY    NORM      L2NORM
   Nodal:    DISPLR    DISPLZ    VELR      VELZ      ACCELR    ACCELZ
   Element:  SIGR      SIGZ      SIGT      TAURZ     EPSR      EPST
             EPSRZ
\end{verbatim}

\verb|ALG>| \cmd{SAVE NODAL}

\begin{comments}
All the input database nodal variables (\cmd{DISPLR}, \cmd{DISPLZ}, \ldots,
\cmd{ACCELZ}) will be written unchanged to the output database (unless
they are assigned a value or listed in a \cmd{DELETE} command).
\end{comments}

\newpage
\verb|ALG>|
\cmd{VONMISES = (1.0$/$SQRT(2.0)) $*$ TMAG(SIGR,SIGZ,SIGT,TAURZ,0,0)} \\
\verb|ALG>|
\cmd{EFFSTR = SQRT(1.5) $*$ 5.79E-3 $*$ VONMISES$**$4 $*$
EXP(-12.0$/$300.0$*$1.987)} \\
\verb|ALG>|
\cmd{PRESS = (SIGR $+$ SIGZ $+$ SIGT) $/$ 3.0} \\
\verb|ALG>|
\cmd{PRESS100 = (SIGR\$100 + SIGZ\$100 + SIGT\$100) $/$ 3.0} \\
\verb|ALG>|
\cmd{PHI = EFFSTR $-$ 0.023 $-$ PRESS $*$ (4.43E$-$8 $-$ 3.7E$-$15 $*$
PRESS)} \\
\verb|ALG>|
\cmd{ALPHA = SIGR\$56} \\
\verb|ALG>|
\cmd{BETA = ALPHA $+$ 1.414}

\begin{comments}
Assign element variables \cmd{VONMISES}, \cmd{EFFSTR}, \cmd{PRESS}, and
\cmd{PHI} and global variables \cmd{PRESS100}, \cmd{ALPHA}, and
\cmd{BETA}. Note that the \cmd{PRESS100} equation could be replaced by
``\cmd{PRESS100 = PRESS\$100}''.
\end{comments}

\verb|ALG>| \cmd{DELETE ALPHA}

\begin{comments}
\cmd{ALPHA} (assigned in the equation ``\cmd{ALPHA = SIGR\$56}'' above)
becomes a temporary variable and will not be written to the output
database.
\end{comments}

\verb|ALG>| \cmd{BAD = (A + 1)) + SIN (1,2)}
\vspace{-\medskipamount}
\begin{verbatim}
*** Expected 1 parameter(s) for function SIN, found 2
*** Parenthesis do not balance
*** "A" is not a database variable
    Equation ignored
\end{verbatim}

\begin{comments}
This equation contains several errors. Each error is flagged and the
equation is ignored.
\end{comments}

\verb|ALG>| \cmd{END}

\begin{comments}
No further user input is accepted and the equation evaluation
begins.
\end{comments}