Reductum_Index - Texas Instruments TI-89 Developer's Manual

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reductum_index

Declaration: EStackIndex reductum_index (EStackIndex i )
Category(ies): Algebra Utilities
Description: If i indexes an ADD_TAG, returns the index of the deeper of its two
operands. Otherwise returns Float0Index if IS_ARITH_APPROX is true and
Integer0Index if IS_ARITH_APPROX is false. Internally-simplified
expressions have the most main term shallowest.
For example:
If i indexes the internally-simplified expression
2 + x + y
then reductum_index(i) returns index(y + 2).
If i indexes the internally-simplified expression (
then reductum_index(i) returns Float0Index if IS_ARITH_APPROX is true
and Integer0Index if IS_ARITH_APPROX is false.
Note that Float0Index and Integer0Index are not ordinarily physically within
the expression indexed by i .
For the default mode IS_RECURSIVE, similar powers of the main variable
are collected.
For example:
If i indexes the internally-simplified expression
x^2 * y + x^2 + 5)
then reductum_index(i) returns index(5).
Internally-simplified differences are represented as sums with negated
subtrahends.
For example:
If i indexes the internally-simplified expression
x L y
then reductum_index(i) returns index(y † (L1)).
i
Inputs:
Outputs: If i indexes an ADD_TAG, returns the index of the deeper of its two
operands. Otherwise returns Float0Index if IS_ARITH_APPROX is true and
Integer0Index if IS_ARITH_APPROX is false.
Assumptions: None
Side Effects: None
TI-89 / TI-92 Plus Developer Guide
Appendix A: System Routines — Algebra Utilities
— Indexes the top tag of an expression.
(continued)
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Beta Version January 26, 2001