Matlab 繪製3D半球

 

 

R=10;
z=real(zeros(201,201));
m=0;
n=0;
step = 0.1;

for x=-R:step:R
  m = m + 1;
  %x
  for y=-sqrt(R*R - x*x):step:sqrt(R*R - x*x)
    %y
    n = int32(y / step) + R / step + 1;
    %n
    z(n, m) = real(sqrt(R*R - x*x - y*y));
  endfor
endfor

%z

mesh(z);

 

另一種方法(from octave)：

function [xx, yy, zz] = sphere (varargin)

  [hax, varargin, nargin] = __plt_get_axis_arg__ ("sphere", varargin{:});

  if (nargin > 1)
    print_usage ();
  elseif (nargin == 1)
    n = varargin{1};
  else
    n = 20;
  endif

  theta = linspace (0, 2*pi, n+1);
  phi = linspace (-pi/2, pi/2, n+1);
  [theta,phi] = meshgrid (theta, phi);

  x = cos (phi) .* cos (theta);
  y = cos (phi) .* sin (theta);
  z = sin (phi);

  if (nargout > 0)
    xx = x;
    yy = y;
    zz = z;
  else
    oldfig = [];
    if (! isempty (hax))
      oldfig = get (0, "currentfigure");
    endif
    unwind_protect
      hax = newplot (hax);

      surf (x, y, z);
    unwind_protect_cleanup
      if (! isempty (oldfig))
        set (0, "currentfigure", oldfig);
      endif
    end_unwind_protect
  endif

endfunction