How to stretch scene to fit graphics view?

I am using Qt and C++ as my environment.

I draw a QGraphicsView in my UI, then create a scene and add lines to that it.

I run through an array of 5000 points and draw lines connecting each point.

QGraphicsScene *scene = new QGraphicsScene();
QPen pen2 = QPen(Qt::blue, 8.0);
int j=1;
for (int i=1; i<5000; i++)
{
    scene->addLine(xArray[i],yArray[i],xArray[j],yArray[j], pen2);
    j++;
}

The problem is that the numbers I am grabbing are very small. e.g., 2.000e-12. The numbers will consistently change based on the application.

How can I adjust my scene to stretch to fill my QGraphicsView.

Now, all I see is a dot in the center of my view.