Graphics Reference
In-Depth Information
the graph is shown in figure 3-16 .
Figure 3-16.
eXerCISe 3-6
Create the graph of the surface of revolution that is turning the function sine (x) around the Z axis. also create the
graph of the surface of revolution rotating the function e ^ x around the Y axis.
to obtain the equation of the surface, on the assumption that the rotation is around the Z axis, consider the graph
of the generating curve y = r(z) in the plane YZ . turning this graph around the Z axis forms a surface of revolution.
the sections with flat z = z0 are circles whose raDius is r (z 0 ) and equation x 2 + y 2 = [r(z 0 )] 2 . that means that the
equation x 2 + y 2 = [r (z)] 2 describes the points on the surface of revolution. for our problem, we have r (z) = Sine (z)
and the curve x 2 + y 2 = sine [z] 2 , which are parametric for the purpose of input for matlaB graphics:
>> r =(0:0.1:2*pi)';
>> t =(-pi:0.1:2*pi);
>> X = cos (r)*sin (t);
>> Y = sin(r)*sin (t);
>> Z = ones (1, size (r))'* t;
>> surf(X,Y,Z), shading interp
this generates the graph in figure 3-17 .
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