Please post a worksheet. There is no way to answer your question without a worksheet showing what you have done. You should not be able to plot ln(x) for any number less than or equal to zero. ln(0) is undefined, and ln(<0) is a complex number.
OK. Now I see what you mean. It's because you are using the Quickplot feature of Mathcad. It chooses the number of points to plot, and the location of those points. If you define x using a range variable you have more control.
