Geoscience Reference
In-Depth Information
ans 1x4 32 double
b 1x1 8 double
Note that by default MATLAB is case sensitive, i.e.,
A
and
a
can dei ne two
dif erent variables. In this context, it is recommended that capital letters be
used for arrays that have two dimensions or more and lower-case letters
for one-dimensional arrays (or vectors) and for scalars. However, it is
also common to use variables with mixed large and small letters. h is is
particularly important when using descriptive variable names, i.e., variables
whose names contain information concerning their meaning or purpose,
such as the variable
CatchmentSize
, rather than a single-character variable
a
.
We could now delete the contents of the variable
ans
by typing
Movie
2.2
clear ans
Next, we will learn how specii c array elements can be accessed or exchanged.
Typing
A(3,2)
simply yields the array element located in the third row and second column,
which is
9
. h e array indexing therefore follows the rule
(row, column)
. We
can use this to replace single or multiple array elements. As an example we
type
A(3,2) = 30
to replace the element
A(3,2)
by
30
and to display the entire array.
A =
2 4 3 7
9 3 -1 2
1 30 3 7
6 6 3 -2
If we wish to replace several elements at one time, we can use the
colon
operator
. Typing
A(3,1:4) = [1 3 3 5]
or
A(3,:) = [1 3 3 5]
replaces all elements of the third row of the array
A
. h e colon operator also
has several other uses in MATLAB, for instance as a shortcut for entering
array elements such as
