Is_Nonnegative - Texas Instruments TI-89 Developer's Manual

Appendix A: System Routines — Logic

is_nonnegative

Declaration: Boolean is_nonnegative (EStackIndex i )
Category(ies): Logic
Description: Determines whether the internally-simplified algebraic expression indexed
by i is non-negative real for all finite values of all variables therein. Takes
into account bounds indexed by NG_such_that_index. ALL zeros are
considered non-negative, even L0 and L0.0
Inputs: i
Outputs: Returns TRUE if it can determine that the internally-simplified algebraic
expression indexed by i is non-negative real for all finite values of all
variables therein. Otherwise returns FALSE, even though the expression
indexed by i might always be non-negative.
Assumptions: None
Side Effects: None
Availability: On AMS 2.02 and higher.
TI-89 / TI-92 Plus
Differences: None
See Also: is_never0, is_positive, is_nonpositive, is0, is_negative, is_real
Example:
EStackIndex index_nonnegative_factor (EStackIndex i)
/* i indexes a term.
Returns NULL_INDEX if it cannot determine that one of its explicit
factors is non-negative.
Otherwise returns i or the index of its first remaining factors for which
the lead factor has been determined to be nonnegative.
*/
{ while (! is1 (i))
if (is_nonnegative (lead_factor_index (i)))
return i;
else
i = remaining_factors_index (i);
return NULL_INDEX;
}
TI-89 / TI-92 Plus Developer Guide
— Index of the top tag of an internally-simplified expression.
Not for Distribution
731
Beta Version January 26, 2001