Datasheet

Floating-point Support
5-28 Copyright © 1999-2001 ARM Limited. All rights reserved. ARM DUI 0067D
5.4.13 Logarithm of one more than x (log1p)
double log1p(double x);
This function computes the natural logarithm of x + 1. Like expm1 , it is better to use this
function than
log(x+1) because this function is more accurate when x is near zero.
5.4.14 Return the exponent of a number (logb)
double logb(double x);
This function is similar to ilogb , but returns its result as a double . It can therefore return
special results in special cases.
•
logb(NaN) is a quiet NaN.
•
logb(infinity) is +infinity.
•
logb(0) is –infinity, and causes a Divide by Zero exception.
logb is the same function as the Logb function described in the IEEE 754 Appendix.
5.4.15 Return the next representable number (nextafter)
double nextafter(double x, double y);
This function returns the next representable number after x, in the direction toward y. If
x and y are equal, x is returned.
5.4.16 IEEE 754 remainder function (remainder)
double remainder(double x, double y);
This function is the IEEE 754 remainder operation. It is a synonym for _drem (see
Arithmetic on numbers in a particular format on page 5-4).
5.4.17 IEEE round-to-integer operation (rint)
double rint(double x);
This function is the IEEE 754 round-to-integer operation. It is a synonym for _drnd (see
Arithmetic on numbers in a particular format on page 5-4).