gen_points.m

椭圆拟合的相关介绍与数学运算方法

function X = gen_points (cmd, a, b, nofpts, myeps, seed);
%GEN_POINTS 	Generate points for fit-ell-lsq
%
%	X = gen_points (cmd, a, b, nofpts, myeps, seed);
%	gets 'nofpts' points, of different kind.
%
  if     (nargin < 6), rand('seed', 0);
  else                 rand('seed', seed);
  end
  if     (nargin < 5), myeps = 0.5;
  end
  if     (nargin < 4), nofpts = 8;
  end
  if     (nargin < 2), a = 20; b = 10;
  elseif (nargin < 3), b = a/2;
  end

  if     (strcmp(cmd, 'spec1')),
    X = a/20*[[1 2 5 7 9 3 6 8]', [7 6 8 7 5 7 2 4]'];
  elseif     (strcmp(cmd, 'spec2')),
    X = a/20*[[1 2 5 7 9 6 3 8]', [7 6 8 7 5 7 2 4]'];
  elseif (strcmp(cmd, 'rand')),
    X = a * rand (nofpts, 2);
  elseif (strcmp(cmd, 'circle')),
    phi = 2 * pi * rand (nofpts, 1);
    X = [a * cos(phi), a * sin(phi)]; 
  elseif (strcmp(cmd, 'circle_rand')),
    phi = 2 * pi * rand (nofpts, 1);
    X = [a * cos(phi), a * sin(phi)] + myeps * a * (rand(nofpts, 2) - 0.5);
  elseif (strcmp(cmd, 'ellipse')),
    phi = 2 * pi * rand (nofpts, 1);
    X = [a * cos(phi), b * sin(phi)]; 
  elseif (strcmp(cmd, 'ellipse_rand')),
    phi = 2 * pi * rand (nofpts, 1);
    X = [a * cos(phi), b * sin(phi)] + myeps * a * (rand(nofpts, 2) - 0.5);
  elseif (strcmp(cmd, 'hyperbola')),
    phi = rand (nofpts, 1) - 1/2;
    phi = phi/log(a+b+2);
    X = [a * cosh(phi), b * sinh(phi)]; 
  elseif (strcmp(cmd, 'hyperbola_rand')),
    phi = rand (nofpts, 1) - 1/2;
    phi = phi/log(a+b+2);
    X = [a * cosh(phi), b * sinh(phi)] + myeps * a * (rand(nofpts, 2) - 0.5);
  elseif (strcmp(cmd, 'ginput1')),
    X = a*[...
    0.0970    0.1877
    0.1432    0.2375
    0.2471    0.3314
    0.2818    0.4076
    0.3256    0.4604
    0.4203    0.5308
    0.4688    0.5777
    0.5289    0.6422
    0.5797    0.7478
    0.6905    0.8123
    0.8176    0.8299
    0.8106    0.6862
    0.7667    0.6246
    0.7367    0.5748
    0.6005    0.4780
    0.5289    0.4106
    0.4688    0.3519
    0.4688    0.3519
    0.3788    0.2199
    0.2910    0.1965
    0.2240    0.1466
    0.1501    0.1349
    ];    
  else
    error ('unknown command');
  end

end % gen_points