Texas Instruments TI-83 PLUS - Manual (Page 494)

TI-83 Plus CATALOG, Strings, Hyperbolic Functions 491
Equ 4 String(
Equ 4 String( converts to a string an equation that is stored to any
VARS
Y . VARS
variable. Y n contains the equation. Str n (from Str1 to Str9 , or Str0 )
is the string variable to which you want the equation to be stored as a
string.
Equ 4 String(Y n ,Str n )
expr(
expr( converts the character string contained in string to an expression
and executes it. string can be a string or a string variable.
expr( string )