dly wrote: > By undefined in J > do you mean a variable to which no value has been assigned? > an attribute that is defined for some but not all? > is it associated with something like null which you can test for? > how does J handle the undefined?
J sometimes assigns definite values to expressions some would consider indeterminate. For heated debate on this topic, search the archives for discussions on 0^0 (I do not want to reopen it). J has a primitive -. (Indeterminate). The Dictionary entry, in full, reads: The indeterminate _. results from expressions such as _-_ (infinity minus infinity) and from expressions (such as 3+_.) in which an indeterminate argument occurs. The official advice from Roger is: However, use of the indeterminate at any time in any circumstance is not recommend. I consider it a data virus, almost as bad as -0 (minus 0). Best wishes, John ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
