Adds a cumulative area plot to an existing graph.


plotAddArea([myPlot, ]x, y[, base])
  • myPlot (struct) – Optional argument, a plotControl structure.
  • x (Nx1 vector) – the X coordinates
  • y (Nx1 or NxM matrix) – Each column contains the height for the corresponding section of the graph. If y contains more than one column, each column will be stacked on top of the previous column.
  • base (scalar) – Optional argument. The height for the base of the added area plot. The default value is zero. plotAddArea() does not yet support a vector input for base.


Creating confidence intervals

// Create the 'x' and 'y' for the normal
// probability density function
x = seqa(-3.5, 0.1, 71);
y = pdfn(x);

// Create the 'x' and 'y' points
// for the left tail
edge = cdfni(0.05);
x_ci = selif(x, (x .< edge));
y_ci = y[1:rows(x_ci)];

// Set colors
struct plotControl myPlot;
myPlot = plotGetDefaults("xy");

clr = getColorPalette("accent", 3);

plotSetLineColor(&myPlot, clr[3]);

plotSetFill(&myPlot, 1, 1, clr[3]);

// Draw filled in left tail
plotArea(myPlot, x_ci, y_ci);

// Create the 'x' and 'y' points
// for the right tail
edge = cdfni(0.95);
x_ci = selif(x, (x .> edge));
y_ci = y[rows(y)-rows(x_ci)+1:rows(y)];

// Add right tail to graph
plotAddArea(myPlot, x_ci, y_ci);

// Add pdfn line
plotSetLineSymbol(&myPlot, -1);
plotAddXY(myPlot, x, y);

The code to create the graph below can be found in the file plotaddci.e in your GAUSS examples directory.

Creating confidence intervals with plotAddArea()



plotAddArea() may only add curves to 2-D graphs.

This function will not change any of the current graph’s settings other than to resize the view as necessary to display the new curve.