is_handle_valid Check whether a set of graphic handles is still valid.

## Syntax

    isValid = is_handle_valid(h)

## Arguments

h

  Matrix of graphic handles

isValid

  Matrix of boolean with the same size as `h`

## Description

`is_handle_valid` function tests whether a set of graphic handle is still valid. A valid handle is a handle which has not been deleted. The result, `isValid`, is a boolean matrix such as `isValid(i,j)` is true if `h(i,j)` is valid and false otherwise.

## Examples

    // check that current objects are valid
    is_handle_valid([gcf(), gca(), gce()])

    // create 11 polylines
    plot([0:10; 0:10; 0:10], [0:10; 0:0.5:5; 0:2:20]);

    // check polylines validity
    axes = gca();
    polylines = axes.children(1).children
    is_handle_valid(polylines)

    // delete some polylines
    delete(polylines(3:7));
    // print validity
    is_handle_valid(polylines)

## See also

- delete
- graphics_entities