Page 37 -

y=a*sin(th);
z=(1+A*cos(w*(t-1)))*th;
plot3(x,y,z,'r');
axis([-2 2 -2 2 0 40*pi]);
M(:,t)=getframe;
end
movie(M,15)

The statement M=moviein(16) creates the 2-D structure that stores in
each column the data corresponding to a frame at a specific time. The frames
themselves are generated within the for loop. The getframe function
returns a pixel image of the image of the different frames. The last command
plays the movie n-times (15, in this instance).

1.10 Histograms

The most convenient representation for data collected from experiments is in
the form of histograms. Typically, you collect data and want to sort it out in
different bins; the MATLAB command for this operation is hist. But prior to
getting to this point, let us introduce some array-related definitions and learn
the use of the MATLAB commands that compute them.
Let {y } be a data set; it can be represented in MATLAB by an array. The
n
largest element of this array is obtained through the command max(y), and
the smallest element is obtained through the command min(y).
The mean value of the elements of the array is obtained through the com-
mand mean(y), and the standard deviation is obtained through the com-
mand std(y).
The definitions of the mean and of the standard deviation are, respectively,
given by:

N
∑ yi ()
y = i=1
N
N
N
∑ 2 −  ∑  2
N (( y i ( ) 
y i))
σ = i=1 i  =1 
y
(
NN − ) 1
where N is the dimension of the array.

© 2001 by CRC Press LLC