Push_Lim - Texas Instruments TI-89 Developer's Manual

794

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
ki
j , direction — Indexes to internally-simplified algebraic expressions.
Outputs: None
Assumptions: None
None
Side Effects:
On AMS 2.02 and higher.
Availability:
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
Appendix A: System Routines — Math
— Indexes the top tag of an internally-simplified algebraic
expression, algebraic comparison, or aggregate thereof.
— Indexes the top tag of a variable.
Not for Distribution Beta Version January 26, 2001