// Set legend box specification
$graph->legend->SetFillColor("white");
$graph->legend->SetLineWeight(2);
// Set X-axis at the minimum value of Y-axis (default will be at 0)
$graph->xaxis->SetPos("min");
// "min" will position the x-axis at the minimum value of the Y-axis
// Extend the margin for the labels on the Y-axis and reverse the direction
// of the ticks on the Y-axis
$graph->yaxis->SetLabelMargin(12);
$graph->xaxis->SetLabelMargin(6);
$graph->yaxis->SetTickSide(SIDE_LEFT);
$graph->xaxis->SetTickSide(SIDE_DOWN);
// Add mark graph with static lines
$line = new PlotLine(HORIZONTAL, 0, "black", 2);
$graph->AddLine($line);
// Create a new impuls type scatter plot
$sp1 = new ScatterPlot($datay, $datax);
$sp1->mark->SetType(MARK_SQUARE);
$sp1->mark->SetFillColor("red");
$sp1->mark->SetWidth(3);
$sp1->SetImpuls();
$sp1->SetColor("blue");
$sp1->SetWeight(1);
$sp1->SetLegend("Non-causal signal");
$graph->Add($sp1);
// Create the envelope plot
$ep1 = new Plot\LinePlot($datayenv, $datax);
$ep1->SetStyle("dotted");
$ep1->SetLegend("Positive envelope");
$graph->Add($ep1);
$graph->Stroke();
