Page 35 - Computational Colour Science Using MATLAB

22 A SHORT INTRODUCTION TO MATLAB

w = linspace(400,700,31);

would generate a 31-dimensional vector containing the values 400, 410, 420, ...,
700 evenly spaced between 400 and 700. In order to discover the operation of
other functions use the help command such as

>>help size
SIZE Size of matrix.
D = SIZE(X), for M-by-N matrix X, returns the two-element
row vector D = [M, N] containing the number of rows
and columns in the matrix. For N-D arrays, SIZE(X) returns
a 1-by-N vector of dimension lengths. Trailing singleton
dimensions are ignored.
[M,N] = SIZE(X) returns the number of rows and columns in
separate output variables. [M1,M2,M3,...,MN] = SIZE(X)
returns the length of the first N dimensions of X.
M = SIZE(X,DIM) returns the length of the dimension
specified by the scalar DIM. For example, SIZE(X,1) returns
the number of rows.
See also LENGTH, NDIMS.

When entering matrices in MATLAB names must begin with a letter, contain
only letters or digits, and although they may be entered of any length, MATLAB
only retains the first 19 characters. During a MATLAB session the values of all
defined variables are stored in the workspace. The user may save the current list
of variables and their associated values using the save command. The command
save myfile.mat, for example, will save the workspace as a special MATLAB
file and this may be recovered during a new session using the load command.
The command clear will remove all user-defined variables from the workspace.
The format of displayed numbers during a session can be changed using the
format command. Finally, it is important to note that MATLAB is case sensitive.

3.2 Computing the transpose and inverse of matrices

A matrix may be easily transposed in MATLAB using the ’ operator. Thus, if x
is a 3 1 column matrix, then the command

x = x’;

will convert x into a 1 3 row matrix.
The inv operator has already been introduced for computing the inverse of a
matrix when solving a pair of simultaneous equations. The inv command can