% Example 4.5a (Physics 330)

clear; close all;

dphi=pi/100; % set the spacing in azimuthal angle

N=30; % set the number of azimuthal trips
phi=0:dphi:N*2*pi;

theta=phi/N/2; % go from north to south once

r=1;  % sphere of radius 1

% convert spherical to Cartesian
x=r*sin(theta).*cos(phi);
y=r*sin(theta).*sin(phi);
z=r*cos(theta);

% plot the spiral
plot3(x,y,z,'b-')
axis equal