Texas Instruments TI-89 - Ng_Such_That_Index

1208
Appendix B: Global Variables — Algebra Utilities
TI
-
89 / TI
-
92 Plus Developer Guide
Not for Distribution
Beta Version January 26, 2001
NG_such_that_index
Declaration:
EStackIndex
NG_such_that_index
Category(ies):
Algebra Utilities
Description:
This global variable is the EStackIndex of the currently active “such that”
expression. When a user enters an expression using the “with” ( | )
operator, the expression to the right of the “with” operator is indexed by
NG_such_that_index
. In addition, various internal system processes may
supplement or override this expression. The entry point
push_substitute_using_such_that
provides a direct way to supplement
or override this expression.
Inputs:
Not applicable.
Outputs:
Not applicable.
Assumptions:
Access_AMS_Global_Variables must be defined.
Side Effects:
Not applicable.
Availability:
On AMS 2.04 and higher.
TI-89 / TI-92 Plus
Differences:
None
See Also: push_substitute_using_such_that
Example:
The expression x + 1 | x = 3 produces the following external tokenized form
3 1 NONNEGATIVE_INTEGER_TAG X_VAR_TAG EQUATION_TAG X_VAR_TAG 1 1
NONNEGATIVE_INTEGER_TAG ADD_TAG SUCH_THAT_TAG
Then, during the evaluation of the expression x + 1, the expression x = 3 is indexed by
NG_such_that_index
at the bolded tag as follows.
3 1 NONNEGATIVE_INTEGER_TAG X_VAR_TAG
EQUATION_TAG
The result is that 3 is substituted for x in the expression x + 1 yielding 4 as the result.