Texas Instruments TI-83 PLUS - Manual (Page 496)

TI-83 Plus CATALOG, Strings, Hyperbolic Functions 493
String 4 Equ(
String 4 Equ( converts string into an equation and stores the equation to Y n .
string can be a string or string variable. String 4 Equ( is the inverse of
Equ 4 String( .
String 4 Equ( string ,Y n )
sub(
sub( returns a string that is a subset of an existing string . string can be a
string or a string variable. begin is the position number of the first
character of the subset. length is the number of characters in the subset.
sub( string , begin , length )