HP Prime Graphing Calculator - Manual (Page 397)

Functions and commands 393
icosahedron Draws an icosahedron with center A, vertex B and such that
the plane ABC contains one vertex among the five nearest
vertices from B.
icosahedron(Pnt(A),Pnt(B),Pnt(C))
id Returns the solution to the identity function for an expression.
id(Seq)
Example:
id(1,2,3)
gives
1,2,3
identity Returns the identity matrix of dimension n.
identity(Intg(n))
Example:
identity(3)
gives
[[1,0,0],[0,1,0],[0,0,1]]
iegcd Returns the extended greatest common divisor of two integers.
iegcd(Intg,Intg)
Example:
iegcd(14, 21)
returns
[-1, 1, 7]
IF Used in programming to begin a conditional statement.
IFERR Executes sequence of commands1. If an error occurs during
execution of commands1, execute sequence of commands2.
Otherwise, execute sequence of commands3.
IFERR commands1 THEN commands2 [ELSE
commands3
] END;
IFTE If a condition is satisfied, returns Expr1, otherwise returns
Expr2.
IFTE(Cond,Expr1,Expr2)
Example:
IFTE(2<3, 5-1, 2+7)
returns
4
igcd Returns the greatest common divisor of two integers or two
rationals or two polynomials of several variables.
igcd((Intg(a) or Poly),(Intg(b) or Poly))
Example:
igcd(24, 36)
returns
12