I need to plot a graph using semilogx(x,y). I have x=[0 1 2 ... 10 15 20 30 50 75 100]. The problem is that MATLAB does not plot x=0, which I understand because log(0)=undef. So is there another method in MATLAB to spread my points? Because using linear scale squeezes all first points in 1/10th of the graph's width!
Usually, what is done in cases like this is adding 1 to all x, so the first value (originally 0) appears at the origin, and also the back-transformation is the same for all values. You can add any other small values than 1, and get a similar result. However, you don't want to add a value that is too small (like eps) because then you get a huge distance from the next value, that will cause all other values to pack on the right side of the graph.
Let's look at an example:
x = [0 logspace(0,2,5)];
% x = 0 1 3.1623 10 31.623 100
y = 2.*(x+1); % add 1 to all x
semilogx(x+1,y,'o','markerfacecolor','b')
While if you replace 0 with eps you get:
x = [0 logspace(0,2,5)];
y = 2.*(x+eps); % add a tiny value too all x
semilogx(x+eps,y,'o','markerfacecolor','b')
来源：https://stackoverflow.com/questions/44680134/how-to-plot-x-0-in-semilogx-plot