errclear clears the last error (if its number matches a given one)

## Syntax

              errclear()
              errclear(n)

## Description

clears the action (error-handler) connected to error of type `n`.

If `n` is positive (n > 0), it is the number of the cleared error ; otherwise if (n <= 0) all errors are cleared (default case).

## Examples

    a = 1;
    try, b = undefinedvariable + a; end
    [m,n0] = lasterror();
    n0
    try, b = undefinedvariable + a; end
    errclear()
    [m,n] = lasterror();
    n
    try, b = undefinedvariable + a; end
    errclear(100)
    [m,n] = lasterror(); n

    try, b = undefinedvariable + a; end
    errclear(999)
    [m,n] = lasterror(); n

    --> try, b = undefinedvariable + a; end
    --> [m,n0] = lasterror();
    --> n0
     n0  =
       999.

    --> try, b = undefinedvariable + a; end
    --> errclear()
    --> [m,n] = lasterror();
    --> n
     n  =
       0.

    --> try, b = undefinedvariable + a; end
    --> errclear(100)
    --> [m,n] = lasterror(); n
     n  =
       999.

    --> try, b = undefinedvariable + a; end
    --> errclear(999)
    --> [m,n] = lasterror(); n
     n  =
       0.

## See also

- lasterror