how to graph equations in kotlin using graphview

Question

I have imported the GraphView library and since its documentation is in good java, it is difficult for me to transcribe it to kotlin, my goal is to graph statistical distributions and for this I have the following formula:

"The goal is to graph as it is in the image below"

Hipotesismedia1Activity.kt

class Hipotesismedia1Activity : AppCompatActivity() {
    lateinit var series1: LineGraphSeries<DataPoint>

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_hipotesismedia1)

        series1 = LineGraphSeries<DataPoint>()
        var x:Double = 0.0
        var y:Double = 0.0
        val sigma = 2.5
        val media = 300.0

        for ( i in 0..295){
            x += i.toDouble()
            y = Math.exp(-((x-media).pow(2))/(sigma* sqrt(2* PI)))/(sigma* sqrt(2* PI))
            series1.appendData(DataPoint(x,y),true,40)
        }
        plot.viewport.setMaxX(350.0)
        plot.addSeries(series1)
        plot.viewport.isXAxisBoundsManual = true
        plot.viewport.isScalable = true
        plot.viewport.isScrollable = true
    }
}

Design XML

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".Hipotesismedia1Activity">

    <com.jjoe64.graphview.GraphView
            android:id="@+id/plot"
            android:layout_width="match_parent"
            android:layout_height="match_parent" app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"/>

</android.support.constraint.ConstraintLayout>

The graph I have is a triangular line, can you please try to correct my error?