A function handle is a pointer to another function and is defined with the syntax
@function-name
For example,
f = @sin;
creates a function handle called f
that refers to the
function sin
.
Function handles are used to call other functions indirectly, or to pass
a function as an argument to another function like quad
or
fsolve
. For example:
f = @sin; quad (f, 0, pi) ⇒ 2
You may use feval
to call a function using function handle, or
simply write the name of the function handle followed by an argument
list. If there are no arguments, you must use an empty argument list
‘()’. For example:
f = @sin; feval (f, pi/4) ⇒ 0.70711 f (pi/4) ⇒ 0.70711
Return true if x is a function handle.
Return a structure containing information about the function handle fcn_handle.
The structure s always contains these three fields:
The function name. For an anonymous function (no name) this will be the actual function definition.
Type of the function.
The function is anonymous.
The function is private.
The function overloads an existing function.
The function is a built-in or m-file function.
The function is a subfunction within an m-file.
The function is nested.
The m-file that will be called to perform the function. This field is empty for anonymous and built-in functions.
In addition, some function types may return more information in additional fields.
Warning: functions
is provided for debugging purposes only.
Its behavior may change in the future and programs should not depend on any
particular output format.
Return a string containing the name of the function referenced by the function handle fcn_handle.
Return a function handle constructed from the string fcn_name.
Previous versions of Octave accepted an optional second argument,
"global"
, that caused str2func to ignore locally visible
functions. This option is no longer supported.
Identify the symbolic variable names in the string str.
Common constant names such as i
, j
, pi
, Inf
and
Octave functions such as sin
or plot
are ignored.
Any names identified are returned in a cell array of strings. The array is empty if no variables were found.
Example:
symvar ("x^2 + y^2 == 4") ⇒ { [1,1] = x [2,1] = y }