5. Monitor Module Algorithms

The monitor module is responsible for printing the run time display of residuals and monitor element values to the screen.

The module allows control over what to display, when to display it and even allows all display information to be switched off. It is possible to select the element, either by element number or by a (x, y, z) position, for which variable values are displayed. The choice of an invalid element number, either too large or too small causes the code to switch off the printing of variable values from the element, but not the variable residuals. The frequency, in terms of iterations between print outs, can be set by the user to limit the expense of screen writing.

The format of the display can be adjusted by the user specifying the number of fraction digits to be used in the printing of real numbers. The number of fraction digits controls the number of decimal places used when a real number is displayed. Consequently, if the number of fraction digits is set to 5 reals will be printed as ' 2.12345E+05'. If zero or a lower number are specified the real value will be displayed as ' 2.E+05'. The main way in which the format of the display can be changed is by switching BLOCK_FORMAT either OFF or ON. The default is OFF which leads to a single line per iteration of the form

     Sim-Time       End-time       Delta-t      Time_step
 [ 6.00000E+01 ][ 1.20000E+03 ][ 6.00000E+01 ][         1 ]
         [--------Residual--------I--------Spot-Value-------]
 Iter.No.           TN           FS           TN           FS
        1  2.40493E+00  5.77006E+00  1.80800E+03  1.00000E+00
       10  1.82917E-02  1.38162E-01  1.80799E+03  1.00000E+00
       20  1.10144E-03  1.05471E-02  1.80799E+03  1.00000E+00
       30  1.32878E-04  2.45208E-03  1.80799E+03  1.00000E+00
       38  4.58676E-05  9.96317E-04  1.80799E+03  1.00000E+00

For a low number of variables this is an excellent format as it allows the values from different iterations to be easily compared and convergence is easily followed. Its major problem comes when there are large numbers of variables. In this case the line wraps around and the columns are not as easy to read. For such a problem the block format should be chosen. This prints each iteration's values in a block with a single line per variable.

 Iter.No.                 285               
 *******************************************
     Var           Residual         Value   
     MASS         3.48099E-04   -9.56736E-06
        P         2.50841E-04    0.00000E+00
        U         7.90646E-04   -4.46446E-02
        V         7.29816E-04    3.50470E-02
        W         0.00000E+00    0.00000E+00
       HN         9.35043E-04    5.19766E+05
     SRAD         3.86210E-04    4.63558E+00
 *******************************************

This format does not allow as easy a comparison between successive iterations as the single line format but it does lead to a much tidier display for the larger number of variables.