<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Function Plot - Implicit Circle</title>
<script src="https://unpkg.com/function-plot/dist/function-plot.js"></script>
</head>
<body>
<div id="circle-implicit"></div>
<script>
functionPlot({
target: '#circle-implicit',
yAxis: { domain: [-1.897959183, 1.897959183] },
xAxis: { domain: [-4, 4] },
data: [
{
fn: '-y*y*(x*x-9)-(x*x+18*y-9)*(x*x+18*y-9)',
fnType: 'implicit'
}
]
});
</script>
</body>
</html>
This plot shouldn't go below the x-axis