FLOOR(3) Linux Programmers Manual FLOOR(3)
floor, floorf, floorl - largest integral value not greater than argu
double floor(double x);
float floorf(float x);
long double floorl(long double x);
Link with -lm.
These functions round x down to the nearest integer.
The rounded integer value. If x is integral or infinite, x itself is
No errors other than EDOM and ERANGE can occur. If x is NaN, then NaN
is returned and errno may be set to EDOM.
The floor() function conforms to SVr4, 4.3BSD, C89. The other func
tions are from C99.
SUSv2 and POSIX.1-2001 contain text about overflow (which might set
errno to ERANGE, or raise an exception). In practice, the result can
not overflow on any current machine, so this error-handling stuff is
just nonsense. (More precisely, overflow can happen only when the max
imum value of the exponent is smaller than the number of mantissa bits.
For the IEEE-754 standard 32-bit and 64-bit floating point numbers the
maximum value of the exponent is 128 (respectively, 1024), and the num
ber of mantissa bits is 24 (respectively, 53).)
ceil(3), lrint(3), nearbyint(3), rint(3), round(3), trunc(3)
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