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diff --git a/man3p/expm1.3p b/man3p/expm1.3p new file mode 100644 index 000000000..0c6e4453d --- /dev/null +++ b/man3p/expm1.3p @@ -0,0 +1,125 @@ +.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved +.TH "EXPM1" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual" +.\" expm1 +.SH NAME +expm1, expm1f, expm1l \- compute exponential functions +.SH SYNOPSIS +.LP +\fB#include <math.h> +.br +.sp +double expm1(double\fP \fIx\fP\fB); +.br +float expm1f(float\fP \fIx\fP\fB); +.br +long double expm1l(long double\fP \fIx\fP\fB); +.br +\fP +.SH DESCRIPTION +.LP +These functions shall compute \fIe**x\fP-1.0. +.LP +An application wishing to check for error situations should set \fIerrno\fP +to zero and call +\fIfeclearexcept\fP(FE_ALL_EXCEPT) before calling these functions. +On return, if \fIerrno\fP is non-zero or +\fIfetestexcept\fP(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) +is non-zero, an error has occurred. +.SH RETURN VALUE +.LP +Upon successful completion, these functions return \fIe**x\fP-1.0. +.LP +If the correct value would cause overflow, a range error shall occur +and \fIexpm1\fP(), \fIexpm1f\fP(), and \fIexpm1l\fP() +shall return the value of the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL, +respectively. +.LP +If +\fIx\fP is NaN, a NaN shall be returned. +.LP +If \fIx\fP is \(+-0, \(+-0 shall be returned. +.LP +If \fIx\fP is -Inf, -1 shall be returned. +.LP +If \fIx\fP is +Inf, \fIx\fP shall be returned. +.LP +If \fIx\fP is subnormal, a range error may occur and \fIx\fP should +be returned. +.SH ERRORS +.LP +These functions shall fail if: +.TP 7 +Range\ Error +The result overflows. +.LP +If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, +then \fIerrno\fP shall be set to [ERANGE]. If the +integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, +then the overflow floating-point exception shall be +raised. +.sp +.LP +These functions may fail if: +.TP 7 +Range\ Error +The value of \fIx\fP is subnormal. +.LP +If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, +then \fIerrno\fP shall be set to [ERANGE]. If the +integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, +then the underflow floating-point exception shall be +raised. +.sp +.LP +\fIThe following sections are informative.\fP +.SH EXAMPLES +.LP +None. +.SH APPLICATION USAGE +.LP +The value of \fIexpm1\fP(\fIx\fP) may be more accurate than \fIexp\fP(\fIx\fP)-1.0 +for small values of \fIx\fP. +.LP +The \fIexpm1\fP() and \fIlog1p\fP() functions are useful for financial +calculations of +((1+\fIx\fP)**\fIn\fP-1)/\fIx\fP, namely: +.sp +.RS +.nf + +\fBexpm1(\fP\fIn\fP \fB* log1p(\fP\fIx\fP\fB))/\fP\fIx\fP +.fi +.RE +.LP +when \fIx\fP is very small (for example, when calculating small daily +interest rates). These functions also simplify writing +accurate inverse hyperbolic functions. +.LP +For IEEE\ Std\ 754-1985 \fBdouble\fP, 709.8 < \fIx\fP implies \fIexpm1\fP( +\fIx\fP) has overflowed. +.LP +On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling +& MATH_ERREXCEPT) are independent of +each other, but at least one of them must be non-zero. +.SH RATIONALE +.LP +None. +.SH FUTURE DIRECTIONS +.LP +None. +.SH SEE ALSO +.LP +\fIexp\fP() , \fIfeclearexcept\fP() , \fIfetestexcept\fP() , \fIilogb\fP() +, \fIlog1p\fP() , +the Base Definitions volume of IEEE\ Std\ 1003.1-2001, Section 4.18, +Treatment of Error Conditions for Mathematical Functions, \fI<math.h>\fP +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. In the +event of any discrepancy between this version and the original IEEE and +The Open Group Standard, the original IEEE and The Open Group Standard +is the referee document. The original Standard can be obtained online at +http://www.opengroup.org/unix/online.html . |