Create an elliptical mask stored as a matrix of logical values.
elliptical_mask(xN, yN, x0, y0, xr, yr, angle)
logical mask matrix with dimensions fov_yN x fov_xN.
number of pixels in the x dimension.
number of pixels in the y dimension.
centre of ellipse in the x direction in units of pixels.
centre of ellipse in the y direction in units of pixels.
radius in the x direction in units of pixels.
radius in the y direction in units of pixels.
angle of rotation in degrees.