A modification of The Mathworks POLAR function, DIRPLOT generates directivity plots in the style commonly used in acoustic and RF work.
1. Plots -90 to +90 or -180 to +180 degrees based on range of input THETA, with 0 degrees at top center.
2. Produces semicircular plots when plot range is -90 to +90 degrees.
3. RHO is assumed to be in decibels and may include negative values.
4. Default automatic rho-axis scaling in "scope knob" factors.
5. Optional PARAMS argument allows manual setting of rho-axis scaling.