Programmazione degli oggetti grafici

Confrontare, verificare la validità, pre-allocare e lavorare con gli array di oggetti

Funzioni

`gobjects`	Initialize array for graphics objects
`isgraphics`	True for valid graphics object handles
`isempty`	Determinare se un array è vuoto
`isequal`	Determine array equality
`isa`	Determine if input has specified data type
`clf`	Clear figure
`cla`	Clear axes
`close`	Close one or more figures

Graphics Object Handles
Use the object handle to set and query the values of the object properties.
Handles in Logical Expressions
Handle objects do not evaluate to logical true or false. You must use the function that tests for the state of interest and returns a logical value.
Graphics Arrays
Graphics arrays can contain the handles of any graphics objects.
Test for Valid Handle
Use isgraphics to determine if a variable is a valid graphics object handle.
Preallocate Arrays of Graphics Objects
Use the gobjects function to preallocate arrays for graphics objects.