Parent function
 | This article needs attention from an expert on the subject. The specific problem is: The definition is not precise, and lacks authoritative references. See the talk page for details. (March 2013) |
| This article needs attention from an expert on the subject. The specific problem is: The definition is not precise, and lacks authoritative references. See the talk page for details. When placing this tag, consider associating this request with a WikiProject. (March 2013) |