Parent Topic: <A href="http://www.pcigeomatics.com/cgi-bin/pcihlp/MODEL">MODEL</a><hr>
<H3>Speed Hints</H3>
Modelling is a very compute intensive process. The modelling
equations are re-executed for each pixel in the database. For
example, a database file with 1000 by 1000 resolution would require
the modelling equations be evaluated 1,000,000 times.<p>
To improve execution speed, MODEL `half' compiles the modelling
equations; however, MODEL basically works as an interpreter. The
following hints can help improve speed even further.<p>
Make equations as simple as possible. For example:
<P>
<PRE>
 replace:  #e = 7 * (%1/2 + 3^2);         
 with:     #e = 3.5 * %1 + 63;
</PRE>
Accessing attribute data is slow. If this data will be used a number
of times in the model, assign it to a numeric/string variable and
use the variable instead. For example:
<P>
<PRE>
 replace:   if (%3.2&gt;27) then #e = %3.2 + ln(%3.2); endif;
 with:      #a = %3.2; if (#a&gt;27) then #e = #a + ln(#a); endif;
</PRE>
Avoid the use of character data where possible. This type of data is
much slower than numeric data.<p>
Please note that comments, blank lines, and white space do not
affect execution speed so they should be used liberally.
<P>
<hr>
Parent Topic: <A href="http://www.pcigeomatics.com/cgi-bin/pcihlp/MODEL">MODEL</a><br>
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