NumberAxis errorAxis = new NumberAxis("Error");
XYPlot plot = (XYPlot) chart.getPlot();
plot.setRangeAxis(1, errorAxis);
plot.setRangeAxisLocation(AxisLocation.TOP_OR_RIGHT);
plot.setDataset(1, errorDataset);
plot.mapDatasetToRangeAxis(1, 1);
XYItemRenderer renderer = new XYLineAndShapeRenderer(true, false);
plot.setRenderer(1, renderer);
float[] err = MU.transpose(error)[dim];
float mse = MU.prod(err, err) / (float) err.length;