说明：  在三维空间中画泡泡,可以指定在三维空间中的x,y,z的坐标以及泡泡的半径r和颜色c(RGB).
(BUBBLEPLOT3(x,y,z,r), where x, y, z and r are four vectors of the same length, plots bubbles of radii r in 3-space with centers at the points whose coordinates are the elements of x, y and z. If r is a matrix of size numel(x)x3, BUBBLEPLOT3 produces ellipsoids with centers x(i),y(i),z(i) and radii r(i,1), r(i,2) and r(i,3). BUBBLEPLOT3(x,y,z,r,c), where c is a rgb-triplet array (in [0,1]) with numel(x) rows, plots bubbles with colours specified by c. )