Singular

5.1.17 defined

Syntax:

defined ( name )

Type:

int

Purpose:

returns a value <>0 (TRUE) if there is a user-defined object with this name, and 0 (FALSE) otherwise.
A non-zero return value is the level where the object is defined (level 1 denotes the top level, level 2 the level of a first procedure, level 3 the level of a procedure called by a first procedure, etc.). For ring variables and other constants, -1 is returned.

Note:

A local object m may be identified by if (defined(m)==voice).

Example:

ring r=(0,t),(x,y),dp; matrix m[5][6]=x,y,1,2,0,x+y; defined(mm); ==> 0 defined(r) and defined(m); ==> 1 defined(m)==voice; // m is defined in the current level ==> 1 defined(x); ==> -1 defined(z); ==> 0 defined("z"); ==> -1 defined(t); ==> -1 defined(42); ==> -1