plotAspectRatio

Description

plotAspectRatio is a specialized plotting utility designed to visualize the distribution of ray angles or “aspect ratio” as a function of grazing angle. It generates a histogram-like plot showing how many times a particular angle is “stacked” given a simulated or theoretical water column height.

This tool is useful for understanding the geometric distribution of sound rays within a given water column and how it relates to aspect ratio or grazing angle.

Usage 

plotAspectRatio [-ar <ratio>] [-outfile <filename.meta>] [-size <dx> <dy>] [-yrange <min> <max>]

Arguments

Option Description Default / Example
-outfile <filename.meta> Specifies the output PostScript metafile name. plot.meta
-size <dx> <dy> Specifies the total plot size in centimeters (X and Y dimensions). 15.0 15.0
-yrange <min> <max> (Present in USAGE but fixed to 0.0 to 25.0 in provided code) Sets the Y-axis range (count or percentage). 0.0 to 25.0
-ar <ratio> Specifies the aspect ratio. This is multiplied by 1000 to get a simulated water column height. (e.g., 0.1 is a low aspect ratio). 1000.0 (implied, as height initialized to 1000.0)

How It Works

  1. Initialization: Parses command-line arguments to set plot size, Y-axis range, and height (which is derived from -ar). Initializes a plotlib PostScript output (plot.meta).
  2. Plot Setup: Sets up the overall plot dimensions (xlength, ylength, xoff, yoff). Draws the main plot border.
  3. Angle Stack Calculation:
    • Initializes a stack[90] array to zeros.
    • Iterates from i = 0 to 999 (simulating horizontal distance).
    • For each i, it calculates an angle (grazing angle) using atan(i / height).
    • Increments stack[(int)angle] for each calculated angle.
    • Scales the stack values by (100.0 / 1000.0) to represent a percentage or normalized count.
    • Determines maxstack from the stack array.
  4. Plotting Histogram:
    • Sets X-axis range from 0.0 to 90.0 (grazing angle).
    • Sets Y-axis range from ymin to ymax (count/percentage).
    • For each j from 0 to 89 (representing angle bins):
      • Draws a vertical bar representing stack[j] as a filled rectangle.
  5. Cleanup: Calls plot_close to finalize the PostScript output.

Output Files

  • <outfile.meta>: A PostScript metafile (.meta) containing a histogram-like plot of angle distribution.

Dependencies

  • plotlib.h: For plotlib functions.
  • support.h: For general utility functions.
  • math.h: For mathematical functions.

Notes

This tool provides a conceptual visualization of how sound rays are distributed as a function of grazing angle, given a simplified model of the water column. This can be used for educational purposes or for understanding the theoretical behavior of sonar systems. The Y-axis range is fixed in the current code, but the usage suggests it could be user-defined.