ARM VERSION 1.2 Datový list stáhnout pdf (Strana 226)

Floating-point Support

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).

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