### 3D plotting

```3D plotting
Recap 2D plotting

plot(x,y): given sequence of x and y values,
connects the dots (x(i),y(i))

Exercise: Plot a circle
>>t=linspace(0,2*pi,100);
>>plot(cos(t),sin(t))
Plot3: Plotting curves in 3D


plot3(x,y,z): Given a sequence of x,y,z values
connects the 3d dots (x(i),y(i),z(i))
Exercise: plot a cylindrical spiral. For a
cylindrical spiral
◦ x=cos(t), y=sin(t), z=t
>>t=linspace(0,8*pi,500);
>>x=cos(t);
>>y=sin(t);
>>z=t;
>>plot3(x,y,z,’o-’);
Exercise

Plot a conical spiral. For a conical spiral
◦ x=t cos(t), y=t sin(t), z=t
surf: Plotting surfaces in 3D


surf(map) plots the function map(i,j) vs j,I

Connects the dots by rectangular patches
◦ (j, i, h(i,j))
◦ (j, i+1, h(j,i+1)
(j+1, i, h(i,j+1))
(j+1,i+1, h(i+1,j+1))
Plotting z(x,y) vs x,y

Plot z=x^2+y^2 vs x,y

[X,Y]=meshgrid(x,y) returns the cartesian
product of the vectors x,y.
>>x=linspace(-5,5,100);
>>y=linspace(-3,3,50);
>>[X,Y]=meshgrid(x,y);
>>surf(X,Y,X.^2+Y.^2);
Exercise

Plot the gaussian function. Its coordinates
are given by
◦ z=exp(-(x^2+y^2)/2)
◦ Assume x,y lie between -5 and 5

Plot a unit sphere. Its coordinates are
given by the equation
◦ x=cos(t)*cos(p), y=cos(t)*sin(p), z=sin(t)
◦ where –pi/2<= t <=pi/2 and 0<=p<=2*pi
```