Is the z-axis in a Sphere only positive?

[X, Y, Z] = sphere(10);
Points = [X(:), Y(:), Z(:)].';
plot3(Points(1,:), Points(2,:), Points(3,:), 'x');

I want to get points by representing only the positive z-axis.

Answer 1

[Chunru]

No. It consists of both positive and negative parts.

[X, Y, Z] = sphere(100);
Points = [X(:), Y(:), Z(:)].';
%plot3(Points(1,:), Points(2,:), Points(3,:), 'x');
surf(X, Y, Z)

whos

  Name          Size                Bytes  Class     Attributes

  Points        3x10201            244824  double              
  X           101x101               81608  double              
  Y           101x101               81608  double              
  Z           101x101               81608  double              
  cmdout        1x33                   66  char                

figure
idx = 51:101;


surf(X(idx, :), Y(idx, :), Z(idx, :))

[민제 강]

So, I want to make it a hemisphere with only positive values on the z-axis.

[Chunru]

See the update.