Plotting Basics in MATLAB

The workhorse function for 2-D visualization in MATLAB is plot(x, y), which draws straight line segments connecting the data points defined by the vectors x and y. If x and y are the same length, MATLAB simply connects (x(1),y(1)) to (x(2),y(2)) and so on; if you omit x entirely and call plot(y), MATLAB uses the vector's index as the x-axis. Every call to plot on a fresh figure clears prior contents unless you explicitly hold the axes, which is why beginners are often surprised when a second plot() call erases the first line instead of adding to it.

MATLAB lets you control appearance with a compact LineSpec string, such as 'r--o', which combines a color (r for red), a line style (-- for dashed), and a marker (o for circle) in any order. For finer control, use name-value pairs like 'Color', [0.2 0.6 0.8], 'LineWidth', 2, or 'MarkerSize', 8 passed directly to plot(). Since R2014b, plot() returns a line object handle (h = plot(x,y)) whose properties can be modified after creation via h.Color = 'g' or set(h, 'LineWidth', 3), which is essential when you need to tweak a plot programmatically rather than re-typing the whole call.

xlabel(), ylabel(), and title() attach text to the current axes, and legend('Series 1', 'Series 2') labels multiple lines drawn on the same axes; the order of legend strings must match the order the lines were plotted. To overlay multiple plots on one set of axes rather than replacing them, call hold on before subsequent plot() calls and hold off when finished. Since R2014b you can also plot multiple series in a single call, plot(x, y1, x, y2, 'r'), which avoids the need for hold entirely and keeps color cycling consistent through the default ColorOrder.