Log Plots in MATLAB^®

Plot One Line

Define x as a vector of 50 logarithmically spaced numbers on the interval [10^-1,10²]. Define y as 2^x. Then plot x and y, and call the grid function to show the grid lines.

x = logspace(-1,2);
y = 2.^x;
loglog(x,y)
grid on

fig2plotly(gcf);

Plot Multiple Lines

Create a vector of x-coordinates and two vectors of y-coordinates. Plot two lines by passing comma-separated x-y pairs to loglog.

x = logspace(-1,2);
y1 = 10.^x;
y2 = 1./10.^x;
loglog(x,y1,x,y2)
grid on

fig2plotly(gcf);

Alternatively, you can create the same plot with one x-y pair by specifying y as a matrix: loglog(x,[y1;y2]).

Specify Axis Labels and Tick Values

Create a set of x- and y-coordinates and display them in a log-log plot.

x = logspace(-1,2,10000);
y = 5 + 3*sin(x);
loglog(x,y)

fig2plotly(gcf);

Call the yticks function to position the y-axis tick values at whole number increments along the y-axis. Then create x- and y-axis labels by calling the xlabel and ylabel functions.

x = logspace(-1,2,10000);
y = 5 + 3*sin(x);
loglog(x,y)

yticks([3 4 5 6 7])
xlabel('x')
ylabel('5 + 3 sin(x)')

fig2plotly(gcf);

Plot Points as Markers Without Lines

Create a set of x- and y-coordinates and display them in a log-log plot. Specify the line style as 's' to display square markers without connecting lines. Specify the marker fill color as the RGB triplet [0 0.447 0.741], which corresponds to a dark shade of blue.

x = logspace(-1,2,20);
y = 10.^x;
loglog(x,y,'s','MarkerFaceColor',[0 0.447 0.741])
grid on

fig2plotly(gcf);

Add a Legend

Create two sets of x- and y-coordinates and display them in a log-log plot. Display a legend in the upper left corner of the plot by calling the legend function and specifying the location as 'northwest'.

x = logspace(-1,2,10000);
y1 = 5 + 3*sin(x/4);
y2 = 5 - 3*sin(x/4);
loglog(x,y1,x,y2,'--')
legend('Signal 1','Signal 2','Location','northwest')

fig2plotly(gcf);