Logarithmic scales
A logarithmic scale is used to examine values that span many orders of magnitude, having application
in various fields, like astronomy, sound level analysis, stock market analysis, etc. A logarithmic
scale increment is based on multiplication, rather than addition. The increment grows exponentially,
by linearly raising the logarithmic base value, starting with exponent 0. For example, a logarithmic
scale of base 10 is increased as follows:
1,10,100,1000,10000, and so on.
A logarithmic scale is always manual and does not support negative
values.
The applet below displays a line series plotted against a logarithmic scale of base 10. The inner
grid lines are enabled.
<applet code="GraphApplet.class" codebase="../../../demo/applets/classes" archive="GraphChart.jar" width=500 height=350>
<!-- Sets some chart properties -->
<param name="bordercolor" value="000000">
<param name="title" value="The JetChart Library,Logarithmic scales">
<param name="verticallabelson" value="yes">
<!-- Enables the grid -->
<param name="graphset0_gridon" value="yes">
<param name="graphset0_gridcolor" value="cccccc">
<!-- Disables automatic scale and enables a logarithmic scale -->
<param name="graphset0_autoscaleon" value="no">
<param name="graphset0_scalelogon" value="yes">
<param name="graphset0_scalelogbase" value="10"> <!-- 10 is default. Just for demonstration purpose. -->
<!-- Enables the inner grid lines and sets the number of inner lines -->
<param name="graphset0_gridinnerloglineson" value="yes">
<param name="graphset0_gridinnerloglinescount" value="10">
<param name="graphset0_scalevalueformat" value="$ ###,###,###">
<param name="graphset0_scalemaxvalue" value="1000000">
<param name="graphset0_scaleminvalue" value="100">
<!-- Sets a xml data source to read series values and chart labels. The 'logchart.xml' file can be found in
the codebase directory -->
<param name="xmldatasourceurl" value="logchart.xml">
<!-- Creates a line series -->
<param name="serie1" value="line,Line series,ff0000">
<param name="serie1_markson" value="no">
<param name="serie1_thickness" value="2">
<!-- Sets the indexes of the only visible scale labels, from top to bottom -->
<param name="graphset0_scalevisiblelabels" value="0,11,22,33,44">
</applet>