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man pages section 3: Extended Library Functions, Volume 2

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Updated: Thursday, June 13, 2019
 
 

fegetprec(3M)

Name

fesetprec, fegetprec - control floating point rounding precision modes

Synopsis

c99 [ flag... ] file... -lm [ library... ]
#include <fenv.h> 

int fesetprec(int prec);
int fegetprec(void);

Description

The IEEE 754 standard defines rounding precision modes for systems that always deliver intermediate results to destinations in extended double precision format. These modes allow such systems to deliver correctly rounded single and double precision results (in the absence of underflow and overflow) with only one rounding.

The fesetprec() function sets the current rounding precision to the precision specified by prec, which must be one of the following values defined in <fenv.h>:

FE_FLTPREC

round to single precision

FE_DBLPREC

round to double precision

FE_LDBLPREC

round to extended double precision

The default rounding precision when a program starts is FE_LDBLPREC.

The fegetprec() function returns the current rounding precision.

Return Values

The fesetprec() function returns a non-zero value if the requested rounding precision is established and 0 otherwise.

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Architecture
Intel (see below)
Availability
system/library/math
Interface Stability
Committed
MT-Level
MT-Safe

These functions are not available on SPARC systems because SPARC processors deliver intermediate results to destinations in single or double format as determined by each floating point instruction.

See Also

fegetenv(3M), fesetround(3M), attributes(7)

Numerical Computation Guide