PK_ATTRIB_ask_vectors

PK_ERROR_code_t     PK_ATTRIB_ask_vectors
(
--- received arguments ---
PK_ATTRIB_t         attrib,         --- attribute
int                 field_no,       --- field number (>= 0)

--- returned arguments ---
int          *const n_vectors,      --- number of vectors (>= 0)
PK_VECTOR_t **const vectors         --- vectors (optional)
)


This function returns the array of vectors from field 'field_no'
of the given attribute.


Specific Errors:
    PK_ERROR_bad_field_number       The attribute does not have a field with
                                    this number
    PK_ERROR_field_of_wrong_type    The field is not a vector, coordinate
                                    or direction field


The field should be of type vector, coordinate or direction.

The output array 'vectors' is optional.  If it is set to NULL, the function
will only return the number of vectors in the field.

See Attribute processing for more information.