POSITIVE_ZERO Constant (Pseudo-constant)

math.h, timath.h

Represents an infinitely small quantity which is known to be always non-negative.

In opposite to UNSIGNED_ZERO, POSITIVE_ZERO is an infinitely small quantity which is known to be always non-negative. It can be imagined as "the smallest positive real number", altough something like this does not exist in reality. TIOS generates POSITIVE_ZERO in cases when the result is zero, but it is known that the result can not be negative for any argument. For example, squaring of ZERO using pow function will return POSITIVE_ZERO, because the square is always non-negative. The same is true for acosh when the argument is equal to 1, etc.

TIOS also generates POSITIVE_ZERO as the result of positive underflow (i.e. when the result is positive, but too small to be represented in a float type), and as the result of rounding extremely small positive numbers using round14 or round12_err. To check whether a value is a positive zero, use is_pzero.

Dividing any finite strictly positive number by POSITIVE_INF will produce POSITIVE_ZERO as the result. Dividing any finite strictly positive number by POSITIVE_ZERO gives POSITIVE_INF, and dividing any finite strictly negative number by POSITIVE_ZERO gives NEGATIVE_INF.

Note: Try in TI Basic '1/0' and '1/0^2' to see that '0' and '0^2' are not strictly the same for TIOS. Clever, isn't it?