HP 48gII - Manual (Page 740)

Page 22-24
It is suggested that you create a separate sub-directory to store the programs.
You could call the sub-directory RIVER, since we are dealing with irregular
open channel cross-sections, typical of rivers.
To see the program XSECT in action, use the following data sets. Enter them
as matrices of two columns, the first column being x and the second one y.
Store the matrices in variables with names such as XYD1 (X-Y Data set 1) and
XYD2 (X-Y Data set 2). To run the program place one of the data sets in the
stack, e.g.,
J @XYD1!, then type in a water surface elevation, say 4.0, and
press @XSECT. The calculator will show an sketch of the cross-section with the
corresponding water surface. To exit the graph display, press $.
Try the following examples:
@XYD1! 2 @XSECT
@XYD1! 3 @XSECT
@XYD1! 4 @XSECT
@XYD1! 6 @XSECT
Please be patient when running program XSECT. Due to the relatively large
number of graphics functions used, not counting the numerical iterations, it
may take some time to produce the graph (about 1 minute).