Why is a best-fit curve jagged?

Why does that curve look so jagged?

The problem is that several data sets were fit at once, and the data sets had very different ranges of X values. The data plotted above was in column A of this data table:

When Prism draws the curve, it gets mixed up. It generates enough line segments to draw a curve that covers the entire span from X=0.01 to 100. But the graph above only covers 3% of that span, and Prism doesn't create enough line segments to make a smooth curve.

There are two alternative workarounds:

• Enter the data sets onto multiple data tables, each that contains data sets with the same (or nearly the same) range of X values.
• Go to the Range tab of nonlinear regression, and enter a large value (try 10,000) for the number of line segments. 

Prism file

Note a related problem with Prism version 1-4. If you stretch the axis to a logarithmic scale (using Format Axes), the curves may be ragged.  This was fixed in Prism 5