Texas Instruments TI-89 - Is_Constant

478
Appendix A: System Routines — EStack Arithmetic
TI
-
89 / TI
-
92 Plus Developer Guide
Not for Distribution
Beta Version January 26, 2001
is_constant
Declaration:
Boolean
is_constant
(EStackIndex
i
)
Category(ies):
EStack Arithmetic
Description:
Determines whether the expression indexed by
i
is a constant.
Inputs:
i
— Index to an expression.
Outputs:
Returns TRUE if the expression indexed by
i
is free of all variables.
Otherwise returns FALSE. Examples include expressions composed of real
or unreal numbers,
p
,
e
, transfinites, true, false, and aggregates thereof.
Assumptions:
i
indexes the top tag of an expression.
Side Effects:
None
Availability:
On AMS 2.02 and higher.
TI
-
89 / TI
-
92 Plus
Differences:
None
See Also: can_be_approxed, is_complex_number, is_complex_float
Examples:
Boolean has_constant_term (EStackIndex i)
/* Returns TRUE if and only if the expression indexed by i has a zero
top-level constant term. */
{ while (! is0 (i))
if (is_constant (lead_term_index (i)))
return TRUE;
else
i = reductum_index (i);
return FALSE;
} /* end has_constant_term */