National Oceanic and
Atmospheric Administration
United States Department of Commerce

Fill between two curves

Fill between two curves

Question:

How can I fill between two curves?

Example:

 

Solution:

 

A script has been contributed by Wiemin Wang and Steve Hankin which uses the POLYGON command to fill between two curves, or a curve and a constant value. The text at the start of the script explains its arguments.

Use the script, fill_between.jnl. It is one of the go scripts included with Ferret. For example,

 yes? DEFINE AXIS/Z=1:100:1 z100
 yes? LET zz = z[gz=z100]
 yes? LET a = SIN(zz/10)- zz/50
 yes? LET b = 3 + COS(zz/4)
 yes? PLOT a,b
 yes? GO fill_between POLY/OVER/NOLABEL/PALETTE=blue a z100 b

Continuing, to make the figure on the right above, we fill between the curve defined by variable b and the vertical line at 3.0. Overlay the curves a and b again for clarity.

 yes? GO fill_between POLY/OVER/NOLABEL/PALETTE=yellow b z100 3.
 yes? PLOT/OVER/NOLAB/COLOR=black a
 yes? PLOT/OVER/NOLAB/COLOR=red b