Texas Instruments TI-89 Developer's Guide

262
Appendix A: System Routines — Algebra Utilities
TI
-
89 / TI
-
92 Plus Developer Guide
Not for Distribution
Beta Version January 26, 2001
lead_term_index
Declaration:
EStackIndex
lead_term_index
(EStackIndex
i
)
Category(ies):
Algebra Utilities
Description:
If
i
indexes an ADD_TAG, returns the index of the shallower of its two
operands. Otherwise returns
i
.
Internally-simplified sums and differences have the most main term
shallowest, with less main terms deeper. Also, the lead term of an
internally-simplified sum is never a sum.
For example:
If i indexes the internally-simplified expression
(2 + x) + y
then
lead_term_index
(i) returns index(x).
If i indexes the internally-simplified expression
x^2 * y
then
lead_term_index
(i) returns index(x^2
†
y).
For the default mode IS_RECURSIVE, similar powers of the main variable
are collected in internally-simplified expressions.
For example:
If i indexes the internally-simplified expression
x^2 * y + x^2 + 5
then
lead_term_index
(i) returns index(x^2
†
(y + 1)).
Inputs:
i
— Index of the top tag of an internally-simplified algebraic expression.
Outputs:
If
i
indexes an ADD_TAG, returns the index of the shallower of its two
operands. Otherwise returns
i
.
Assumptions:
None
Side Effects:
None
Availability:
All versions of the TI
-
89 / TI
-
92 Plus.
TI
-
89 / TI
-
92 Plus
Differences:
None
See Also: reductum_index, lead_factor_index, remaining_factors_index
(continued)

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