"Warning: Negative data ignored" for title(), xlabel(), ylabel()

When I am plotting using the logarithmic scale, either semilogx() or set(gca,'xscale','log') will cause the title(), xlabel(), and ylabel() to generate Negative data ignored warning. The warning disappears when all of those are commented out or deleted, but a plot without title and labels just doesn't seem right. Anyone can help me with why this is happening and are there any ways to resolve this?

Answer 1

[Chunru]

There is no problem except for the warning:

x=(-1:.1:10); semilogx(x, cos(x))
xlabel('x')

Warning: Negative data ignored

ylabel('y')
title('test')