Texas Instruments TI-89 Developer's Guide

734
Appendix A: System Routines — Logic
TI
-
89 / TI
-
92 Plus Developer Guide
Not for Distribution
Beta Version January 26, 2001
is_real
Declaration:
Boolean
is_real
(EStackIndex
i
)
Category(ies):
Logic
Description:
Determine whether the internally-simplified algebraic expression indexed
by
i
is real for all finite real values of all variables therein.
Inputs:
i
— Index of the top tag of an internally-simplified expression or an
aggregate thereof.
Outputs:
Returns TRUE if it can determine that the internally-simplified algebraic
expression indexed by
i
is real for all finite real values of all variables
therein. Otherwise returns FALSE, even though the expression might
always be real.
Assumptions:
None
Side Effects:
None
Availability:
On AMS 2.02 and higher.
TI
-
89 / TI
-
92 Plus
Differences:
None
See Also:
None
Example:
void push_real_factors (EStackIndex i)
/* Pushes the product of the decidably real factors of i. */
{ if (MULTIPLY_TAG == ESTACK (i))
{ push_real_factors (next_expression_index (--i));
if (is_real (i))
times_top (i);
}
else if (is_real (i))
push_expression (i);
else
push_expression (Integer1Index);
}

Texas Instruments TI-89 Specifications

General

Display size (HxV)	100 x 160 mm
Memory type	639K FLASH ROM, 188K bytes RAM
Compatible operating systems	Operating System 2.09
Battery type	AAA