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.TH LDEXP 3M "Jul 12, 2006" "SunOS 5.11" "Mathematical Library Functions"
.SH NAME
ldexp, ldexpf, ldexpl \- load exponent of a floating point number
.SH SYNOPSIS
.LP
.nf
c99 [ \fIflag\fR... ] \fIfile\fR... \fB-lm\fR [ \fIlibrary\fR... ]
#include <math.h>

\fBdouble\fR \fBldexp\fR(\fBdouble\fR x, \fBint\fR exp);
.fi

.LP
.nf
\fBfloat\fR \fBldexpf\fR(\fBfloat\fR x, \fBint\fR exp);
.fi

.LP
.nf
\fBlong double\fR \fBldexpl\fR(\fBlong double\fR x, \fBint\fR exp);
.fi

.SH DESCRIPTION
.sp
.LP
These functions computes the quantity x\|* 2^exp.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, these functions return \fIx\fR multiplied by 2
raised to the power \fIexp\fR.
.sp
.LP
If these functions would cause overflow, a range error occurs and
\fBldexp()\fR, \fBldexpf()\fR, and \fBldexpl()\fR return \fB\(+-HUGE_VAL\fR,
\fB\(+-HUGE_VALF\fR, and \fB\(+-HUGE_VALL\fR (according to the sign of
\fIx\fR), respectively.
.sp
.LP
If \fIx\fR is NaN, a NaN is returned.
.sp
.LP
If \fIx\fR is \(+-0 or \(+-Inf, \fIx\fR is returned.
.sp
.LP
If \fIexp\fR  is 0, \fIx\fR is returned.
.SH ERRORS
.sp
.LP
These functions will fail if:
.sp
.ne 2
.mk
.na
\fBRange Error\fR
.ad
.RS 15n
.rt
The result overflows.
.sp
If the integer expression (\fBmath_errhandling\fR & \fBMATH_ERREXCEPT\fR) is
non-zero, the overflow floating-point exception is raised.
.sp
The \fBldexp()\fR function sets \fBerrno\fR to \fBERANGE\fR if the result
overflows.
.RE

.SH USAGE
.sp
.LP
An application wanting to check for exceptions should call
\fBfeclearexcept\fR(\fBFE_ALL_EXCEPT\fR) before calling these functions. On
return, if \fBfetestexcept\fR(\fBFE_INVALID\fR | \fBFE_DIVBYZERO\fR |
\fBFE_OVERFLOW\fR | \fBFE_UNDERFLOW\fR) is non-zero, an exception has been
raised. An application should either examine the return value or check the
floating point exception flags to detect exceptions.
.sp
.LP
An application can also set \fBerrno\fR to 0 before calling \fBldexp()\fR. On
return, if \fBerrno\fR is non-zero, an error has occurred. The \fBldexpf()\fR
and \fBldexpl()\fR functions do not set \fBerrno\fR.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
tab(	) box;
cw(2.75i) |cw(2.75i)
lw(2.75i) |lw(2.75i)
.
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR frexp (3M),
.BR isnan (3M),
.BR modf (3M),
.BR attributes (7),
.BR standards (7)