Class: ezcGraphChartElementLogarithmicalAxis  - X-Ref

Class to represent a logarithmic axis.

Axis elements represent the axis in a bar, line or radar chart. They are
chart elements (ezcGraphChartElement) extending from
ezcGraphChartElementAxis, where additional formatting options can be found.
You should generally use the axis, which matches your input data best, so
that the automatic chart layouting works best. Aavailable axis types are:

- ezcGraphChartElementDateAxis
- ezcGraphChartElementLabeledAxis
- ezcGraphChartElementLogarithmicalAxis
- ezcGraphChartElementNumericAxis

Logarithmic axis are normally used to display very large or small values.
Logarithmic axis can not be used for value spans including zero, so you
should either pass only positive or only negative values to the chart.

By default the axis uses a base of 10 for scaling, you may assign any other
base to the $base property of the chart. With a base of 10 the steps on the
axis may, for example, be at: 1, 10, 100, 1000, 10000, ...

The logarithmic axis may be used like:

<code>
$graph = new ezcGraphLineChart();
$graph->title = 'The power of x';
$graph->legend->position = ezcGraph::BOTTOM;

$graph->xAxis = new ezcGraphChartElementNumericAxis();
$graph->yAxis = new ezcGraphChartElementLogarithmicalAxis();

$graph->data['x^2'] = new ezcGraphNumericDataSet(
-10, 10,
create_function( '$x', 'return pow( $x, 2 ) + 1;' )
);

$graph->data['x^4'] = new ezcGraphNumericDataSet(
-10, 10,
create_function( '$x', 'return pow( $x, 4 ) + 1;' )
);

$graph->data['x^6'] = new ezcGraphNumericDataSet(
-10, 10,
create_function( '$x', 'return pow( $x, 6 ) + 1;' )
);

$graph->render( 400, 250, 'tutorial_axis_logarithmic.svg' );
</code>