Developer Guide and Reference

  • 2021.2
  • 04/07/2021
  • Public Content
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Contents

Nearest Integer Functions

Many routines in the Intel® Math Library are more optimized for Intel® microprocessors than for non-Intel microprocessors.
The
mathimf.h
header file includes prototypes for Intel® Math Library functions.
The Intel® Math Library supports the following nearest integer functions:

ceil

Description:
The
ceil
function returns the smallest integral value not less than
x
as a floating-point number.
Calling interface:
double ceil(double x);
long double ceill(long double x);
float ceilf(float x);

floor

Description:
The
floor
function returns the largest integral value not greater than
x
as a floating-point value.
Calling interface:
double floor(double x);
long double floorl(long double x);
float floorf(float x);

llrint

Description:
The
llrint
function returns the rounded integer value (according to the current rounding direction) as a
long long int
.
errno
: ERANGE, for values too large
Calling interface:
long long int llrint(double x);
long long int llrintl(long double x);
long long int llrintf(float x);

llround

Description:
The
llround
function returns the rounded integer value as a
long long int
.
errno
: ERANGE, for values too large
Calling interface:
long long int llround(double x);
long long int llroundl(long double x);
long long int llroundf(float x);

lrint

Description:
The
lrint
function returns the rounded integer value (according to the current rounding direction) as a
long int
.
errno
: ERANGE, for values too large
Calling interface:
long int lrint(double x);
long int lrintl(long double x);
long int lrintf(float x);

lround

Description:
The
lround
function returns the rounded integer value as a
long int
. Halfway cases are rounded away from zero.
errno
: ERANGE, for values too large
Calling interface:
long int lround(double x);
long int lroundl(long double x);
long int lroundf(float x);

modf

Description:
The
modf
function returns the value of the signed fractional part of
x
and stores the integral part at
*iptr
as a floating-point number.
Calling interface:
double modf(double x, double *iptr);
long double modfl(long double x, long double *iptr);
float modff(float x, float *iptr);

nearbyint

Description:
The
nearbyint
function returns the rounded integral value as a floating-point number, using the current rounding direction.
Calling interface:
double nearbyint(double x);
long double nearbyintl(long double x);
float nearbyintf(float x);

rint

Description:
The
rint
function returns the rounded integral value as a floating-point number, using the current rounding direction.
Calling interface:
double rint(double x);
long double rintl(long double x);
float rintf(float x);

round

Description:
The
round
function returns the nearest integral value as a floating-point number. Halfway cases are rounded away from zero.
Calling interface:
double round(double x);
long double roundl(long double x);
float roundf(float x);

trunc

Description:
The
trunc
function returns the truncated integral value as a floating-point number.
Calling interface:
double trunc(double x);
long double truncl(long double x);
float truncf(float x);

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.