2004-11-03 13:51:07 +00:00
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.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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2007-06-20 22:33:04 +00:00
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.TH "EXP" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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2004-11-03 13:51:07 +00:00
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.\" exp
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2007-09-20 06:03:25 +00:00
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.SH PROLOG
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This manual page is part of the POSIX Programmer's Manual.
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The Linux implementation of this interface may differ (consult
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the corresponding Linux manual page for details of Linux behavior),
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or the interface may not be implemented on Linux.
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2004-11-03 13:51:07 +00:00
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.SH NAME
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exp, expf, expl \- exponential function
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.SH SYNOPSIS
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.LP
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\fB#include <math.h>
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.br
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.sp
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double exp(double\fP \fIx\fP\fB);
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.br
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float expf(float\fP \fIx\fP\fB);
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.br
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long double expl(long double\fP \fIx\fP\fB);
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.br
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\fP
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.SH DESCRIPTION
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.LP
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These functions shall compute the base- \fIe\fP exponential of \fIx\fP.
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.LP
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An application wishing to check for error situations should set \fIerrno\fP
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to zero and call
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\fIfeclearexcept\fP(FE_ALL_EXCEPT) before calling these functions.
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On return, if \fIerrno\fP is non-zero or
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\fIfetestexcept\fP(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW)
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is non-zero, an error has occurred.
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.SH RETURN VALUE
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.LP
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Upon successful completion, these functions shall return the exponential
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value of \fIx\fP.
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.LP
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If the correct value would cause overflow, a range error shall occur
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and \fIexp\fP(), \fIexpf\fP(), and \fIexpl\fP() shall
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return the value of the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL,
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respectively.
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.LP
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If the correct value would cause underflow, and is not representable,
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2007-11-18 06:52:48 +00:00
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a range error may occur, and either 0.0 (if
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supported), or an implementation-defined value shall be
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2004-11-03 13:51:07 +00:00
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returned.
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.LP
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If
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\fIx\fP is NaN, a NaN shall be returned.
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.LP
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If \fIx\fP is \(+-0, 1 shall be returned.
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.LP
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If \fIx\fP is -Inf, +0 shall be returned.
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.LP
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If \fIx\fP is +Inf, \fIx\fP shall be returned.
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.LP
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If the correct value would cause underflow, and is representable,
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a range error may occur and the correct value shall be
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returned.
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.SH ERRORS
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.LP
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These functions shall fail if:
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.TP 7
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Range\ Error
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The result overflows.
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.LP
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If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
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then \fIerrno\fP shall be set to [ERANGE]. If the
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integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero,
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then the overflow floating-point exception shall be
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raised.
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.sp
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.LP
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These functions may fail if:
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.TP 7
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Range\ Error
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The result underflows.
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.LP
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If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
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then \fIerrno\fP shall be set to [ERANGE]. If the
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integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero,
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then the underflow floating-point exception shall be
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raised.
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.sp
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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Note that for IEEE\ Std\ 754-1985 \fBdouble\fP, 709.8 < \fIx\fP implies
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\fIexp\fP( \fIx\fP) has overflowed. The
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value \fIx\fP <\ -708.4 implies \fIexp\fP( \fIx\fP) has underflowed.
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.LP
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On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling
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& MATH_ERREXCEPT) are independent of
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each other, but at least one of them must be non-zero.
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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2007-09-20 17:56:19 +00:00
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\fIfeclearexcept\fP(), \fIfetestexcept\fP(), \fIisnan\fP(), \fIlog\fP(),
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the Base Definitions volume of
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2004-11-03 13:51:07 +00:00
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IEEE\ Std\ 1003.1-2001, Section 4.18, Treatment of Error Conditions
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for
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Mathematical Functions, \fI<math.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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