Texas Instruments TI-89 Developer's Guide

714
Appendix A: System Routines — Lists and Matrices
TI
-
89 / TI
-
92 Plus Developer Guide
Not for Distribution
Beta Version January 26, 2001
push_sign
Declaration:
void
push_sign
(EStackIndex
k
)
Category(ies):
Lists and Matrices
Description:
Pushes the sign of the expression indexed by
k
onto the estack.
sign(positive) -> 1, sign(+0) -> 1, and sign(+0.0) -> 1;
sign(negative) ->
L
1, sign(
L
0) ->
L
1, and sign(
L
0.0) ->
L
1;
sign(+
L
infinity) -> sign(0) and sign(+
L
FloatInfinity) -> sign(0.0);
sign(undef) -> sign(0) and sign(NAN) -> sign(0).
For unreal z, sign(z) -> z/abs(z).
If IS_DOMAIN_REAL sign(0) and sign(0.0) represent +
L
1 and display that
way.
If IS_DOMAIN_COMPLEX, sign(0) displays as sign(0) and sign(0.0)
displays as sign(0.0), both representing the unit circle in the complex plane.
Inputs:
k
— Indexes the top tag of an internally-simplified algebraic expression,
algebraic comparison, or aggregate thereof.
Outputs:
None
Assumptions:
None
Side Effects:
None
Availability:
On AMS 2.02 and higher.
TI
-
89 / TI
-
92 Plus
Differences:
None
See Also:
None
Example:
push_Float (-3.7);
push_sign (top_estack); /* Pushes –1.0 onto the estack. */

Texas Instruments TI-89 Specifications

General

Display size (HxV)	100 x 160 mm
Memory type	639K FLASH ROM, 188K bytes RAM
Compatible operating systems	Operating System 2.09
Battery type	AAA