x02 Chapter Contents
x02 Chapter Introduction
NAG C Library Manual

NAG Library Function Documentnag_real_safe_small_number (X02AMC)

1  Purpose

nag_real_safe_small_number (X02AMC) returns the safe range of floating point arithmetic.

2  Specification

 #include #include
 double nag_real_safe_small_number

3  Description

nag_real_safe_small_number (X02AMC) is a constant defined in the C Header file.
nag_real_safe_small_number (X02AMC) is defined to be the smallest positive model number $z$ such that for any $x$ in the range [$z,1/z$] the following can be computed without undue loss of accuracy, overflow, underflow or other error:
• $-x$
• $1/x$
• $-1/x$
• $\sqrt{x}$
• $\mathrm{log}\left(x\right)$
• $\mathrm{exp}\left(\mathrm{log}\left(x\right)\right)$
• ${y}^{\left(\mathrm{log}\left(x\right)/\mathrm{log}\left(y\right)\right)}$ for any $y$

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