在Matlab茎图中更改轴范围

Question

The x-axis range seems to begin at the first data point and end at the last by default. I'd like to extend this a little bit in both directions so my graph looks zoomed out a bit. How do I set this? I don't see it in the stem documentation.

example code:

f = [0.0 0.45 0.55 1.0];
a = [1.0 1.0 0.0 0.0];

filter = firpm(10,f,a);

plot(f,a);
stem(filter);

and I want to change the x-axis from 0 to 20 (it currently defaults at 1 to 11).

Answer 1

This is not done by stem or any other plotting function. To control axis range you use either axis :

axis(limits) specifies the limits for the current axes. Specify the limits as vector of four, six, or eight elements. [...]

or xlim :

xlim(limits) specifies the x-axis limits for the current axes. Specify limits as a two-element vector of the form [xmin xmax] , where xmax is greater than xmin . [...]
xl = xlim returns a two-element vector containing the current limits. [...]

For example, to extend the current range of the x axis 1 unit to each side:

xlim(xlim + [-1 1])

(note that this uses the two types of calls described in the xlim documentation excerpts above).

Or, in your specific example,

xlim([0 20])