Graphics Programs Reference
In-Depth Information
Sometimes you need to convert one data class into another to prepare the
output of one command to serve as the input for another. For example, to use
plot
on a symbolic expression obtained from
solve
, it is convenient to use
first
vectorize
and then
inline
, because
inline
does not allow symbolic
input and
vectorize
converts symbolic expressions to strings. You can make
the same conversion without vectorizing the expression using
char
. Other
useful conversion commands we have encountered are
double
(symbolic to
numerical),
sym
(numerical or string to symbolic), and
inline
itself (string to
inline function). Also, the commands
num2str
and
str2num
convert between
numbers and strings.
String Manipulation
Oftenitisusefultoconcatenatetwoormorestringstogether.Thesimplestway
to do this is to use MATLAB's vector notation, keeping in mind that a string is
a “row vector” of characters. For example, typing
[string1, string2]
com-
bines
string1
and
string2
into one string.
Here is a useful application of string concatenation. You may need to define
a string variable containing an expression that takes more than one line to
type. (In most circumstances you can continue your MATLAB input onto the
next line by typing
...
followed by
ENTER
or
RETURN
, but this is not allowed
in the middle of a string.) The solution is to break the expression into smaller
parts and concatenate them, as in:
>> eqn = ['left hand side of equation = ', ...
'right hand side of equation']
eqn =
left hand side of equation = right hand side of equation
Symbolicand Floating Point Numbers
We mentioned above that you can convert between symbolic numbers and
floating point numbers with
double
and
sym
. Numbers that you type are,
by default, floating point. However, if you mix symbolic and floating point
numbers in an arithmetic expression, the floating point numbers are auto-
matically converted to symbolic. This explains why you can type
syms x
and
then
xˆ2
without having to convert
2
to a symbolic number. Here is another
example:
>>a=1
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