Texas Instruments TI89 Developer Guide - Page 836

794 Appendix A: System Routines - Math push_lim Declaration: void push_lim (EStackIndex i, EStackIndex ki, EStackIndex j, EStackIndex direction) Category(ies): Math Description: Pushes the limit of expression i, as variable ki approaches expression j. Subject to overriding for consistency with a signed zero or infinity for point j, the limit is from the right if the expression indexed by direction is positive, versus from the left if negative, or from both directions otherwise. If invoked via push_internal_simplify, ki and i are simplified to deepest variable. Moreover, the simplification of i and the computation of the limit are done in the context of a "such that" constraining ki to a small (but finite) neighborhood of point j, from the direction(s) specified by direction. Inputs: i - Indexes the top tag of an internally-simplified algebraic expression, algebraic comparison, or aggregate thereof. ki - Indexes the top tag of a variable. j, direction - Indexes to internally-simplified algebraic expressions. Outputs: None Assumptions: None Side Effects: None Availability: On AMS 2.02 and higher. TI-89 / TI-92 Plus Differences: None See Also: push_substitute_simplify, push_subst_no_simp Example: void push_subst_or_lim (EStackIndex i, EStackIndex ki, EStackIndex j) /* Pushes the result of substituting j for ki in i, unless it yields a nonunique result and the two-sided limit does not, in which case it pushes the latter instead. */ { Access_AMS_Global_Variables; EStackIndex k, old_top = top_estack; push_substitute_simplify (i, ki, j); k = top_estack; if (is_undefined (k)) { push_lim (i, ki, j, Integer0Index); if (is_undefined (top_estack)) top_estack = k; else delete_between (old_top, k); } } /* end push_subst_or_lim */ TI-89 / TI-92 Plus Developer Guide Not for Distribution Beta Version January 26, 2001