KoolChart can handle the negative value.
<?php
/*
* This file is ready to run as standalone example. However, please do:
* 1. Add tags <html><head><body> to make a complete page
* 2. Change relative path in $KoolControlFolder variable to correctly point to KoolControls folder
*/
$KoolControlsFolder = "../../../../KoolControls";//Relative path to "KoolPHPSuite/KoolControls" folder
require $KoolControlsFolder."/KoolChart/koolchart.php";
$chart = new KoolChart("chart");
$chart->scriptFolder=$KoolControlsFolder."/KoolChart";
$chart->Height = 450;
$chart->Width = 500;
$chart->Title->Text = "Bar Chart with negative values";
$chart->Legend->Appearance->Visible = false;
$chart->PlotArea->XAxis->Title = "";
$chart->PlotArea->XAxis->MajorTickSize = 2;
$chart->PlotArea->YAxis->Title = "";
$chart->PlotArea->YAxis->MaxValue = 50;
$chart->PlotArea->YAxis->MinValue = -30;
$chart->PlotArea->YAxis->MajorStep = 10;
$chart->PlotArea->YAxis->MinorStep = 2;
$series = new BarSeries();
$series->Appearance->BackgroundColor = "#399C48";
$series->ArrayData(array(25,-12,39));
$chart->PlotArea->AddSeries($series);
$series = new BarSeries();
$series->Appearance->BackgroundColor = "#28A1DA";
$series->ArrayData(array(-15,38,-11));
$chart->PlotArea->AddSeries($series);
$chart_scatter = new KoolChart("chart_scatter");
$chart_scatter->scriptFolder=$KoolControlsFolder."/KoolChart";
$chart_scatter->Title->Text = "ScatterLine with negative values";
$chart_scatter->Width = 500;
$chart_scatter->Legend->Appearance->Visible = false;
$chart_scatter->PlotArea->XAxis->Title = "";
$chart_scatter->PlotArea->XAxis->MaxValue = 100;
$chart_scatter->PlotArea->XAxis->MinValue = -60;
$chart_scatter->PlotArea->XAxis->MajorStep = 20;
$chart_scatter->PlotArea->XAxis->MinorStep = 4;
$chart_scatter->PlotArea->YAxis->Title = "";
$chart_scatter->PlotArea->YAxis->MaxValue = 60;
$chart_scatter->PlotArea->YAxis->MinValue = -60;
$chart_scatter->PlotArea->YAxis->MajorStep = 10;
$chart_scatter->PlotArea->YAxis->MinorStep = 2;
$series = new ScatterLineSeries();
$series->Appearance->BackgroundColor = "#90B720";
$series->LabelsAppearance->DataFormatString = "{0},{1}";
$series->LabelsAppearance->Position = "Above";
$series->TooltipsAppearance->DataFormatString = "{0},{1}";
$series->TooltipsAppearance->BackgroundColor = "#90B720";
$series->AddItem(new ScatterItem(-27,35));
$series->AddItem(new ScatterItem(14,2));
$series->AddItem(new ScatterItem(50,39));
$chart_scatter->PlotArea->AddSeries($series);
$series = new ScatterLineSeries();
$series->Appearance->BackgroundColor = "orange";
$series->LabelsAppearance->DataFormatString = "{0},{1}";
$series->LabelsAppearance->Position = "Above";
$series->TooltipsAppearance->DataFormatString = "{0},{1}";
$series->TooltipsAppearance->BackgroundColor = "orange";
$series->AddItem(new ScatterItem(-33,15));
$series->AddItem(new ScatterItem(-5,48));
$series->AddItem(new ScatterItem(60,-42));
$chart_scatter->PlotArea->AddSeries($series);
?>
<form id="form1" method="post">
<div>
<?php echo $chart->Render();?>
</div>
<div>
<?php echo $chart_scatter->Render();?>
</div>
<div><i>* <u>Note</u>:</i>Generate your own chart with <a style="color:#B8305E;" target="_blank" href="http://codegen.koolphp.net/generate_koolchart.php">Code Generator</a></div>
</form>
KoolChart - Excellent PHP Chart and GraphFullVersion 2.6.0.2 released on 25/11/2016