plotting a vertical line in matlab?

Hey guys,

I am trying to plot a vertical line in matlab. i need to be able to change its thickness and its color. I will be plotting several vertical lines. I need to plot it at a specific point on the x-axis, and it needs to extend vertically in both directions.

Here is what I have so far:

figure;
clf;
plot(TimeNum,AirTemp1,'k.','LineWidth',1.2);
datetick('x','HH:MM:SS');
xlabel('Time'); ylabel('Temp. (deg-C)'); grid on;
line([x(668) x(668)],[-3.2 -2.8]);
set(gca,'YLim',[-3.2 -2.8])

I dont know why, but my line doesn't show up. Any help would be much appreciated!

[Sarah]

oh sorry, i almost forgot, here is the error notice:

??? Undefined function or method 'x' for input arguments of type

'double'.

Answer 1

[Geoff]

As the error says, you don't have a variable called x and so you can't ask for the 668th element.

You might mean this:

line([668 668],[-3.2 -2.8]);

Answer 2

[Walter Roberson]

Your code

line([x(668) x(668)],[-3.2 -2.8]);

is fine. Just add appropriate options like 'LineWidth' and 'Color'.