| @node Math |
| @chapter Mathematical Functions (@file{math.h}) |
| |
| This chapter groups a wide variety of mathematical functions. The |
| corresponding definitions and declarations are in @file{math.h}. |
| Two definitions from @file{math.h} are of particular interest. |
| |
| @enumerate |
| @item |
| The representation of infinity as a @code{double} is defined as |
| @code{HUGE_VAL}; this number is returned on overflow by many functions. |
| |
| @item |
| The structure @code{exception} is used when you write customized error |
| handlers for the mathematical functions. You can customize error |
| handling for most of these functions by defining your own version of |
| @code{matherr}; see the section on @code{matherr} for details. |
| @end enumerate |
| |
| @cindex system calls |
| @cindex support subroutines |
| @cindex stubs |
| @cindex OS stubs |
| Since the error handling code calls @code{fputs}, the mathematical |
| subroutines require stubs or minimal implementations for the same list |
| of OS subroutines as @code{fputs}: @code{close}, @code{fstat}, |
| @code{isatty}, @code{lseek}, @code{read}, @code{sbrk}, @code{write}. |
| @xref{syscalls,,System Calls, libc.info, The Red Hat newlib C Library}, |
| for a discussion and for sample minimal implementations of these support |
| subroutines. |
| |
| Alternative declarations of the mathematical functions, which exploit |
| specific machine capabilities to operate faster---but generally have |
| less error checking and may reflect additional limitations on some |
| machines---are available when you include @file{fastmath.h} instead of |
| @file{math.h}. |
| |
| @menu |
| * version:: Version of library |
| * acos:: Arccosine |
| * acosh:: Inverse hyperbolic cosine |
| * asin:: Arcsine |
| * asinh:: Inverse hyperbolic sine |
| * atan:: Arctangent |
| * atan2:: Arctangent of y/x |
| * atanh:: Inverse hyperbolic tangent |
| * jN:: Bessel functions (jN, yN) |
| * cbrt:: Cube root |
| * copysign:: Sign of Y, magnitude of X |
| * cosh:: Hyperbolic cosine |
| * erf:: Error function (erf, erfc) |
| * exp:: Exponential |
| * expm1:: Exponential of x, - 1 |
| * fabs:: Absolute value (magnitude) |
| * floor:: Floor and ceiling (floor, ceil) |
| * fmod:: Floating-point remainder (modulo) |
| * frexp:: Split floating-point number |
| * gamma:: Logarithmic gamma function |
| * hypot:: Distance from origin |
| * ilogb:: Get exponent |
| * infinity:: Floating infinity |
| * isnan:: Check type of number |
| * ldexp:: Load exponent |
| * log:: Natural logarithms |
| * log10:: Base 10 logarithms |
| * log1p:: Log of 1 + X |
| * matherr:: Modifiable math error handler |
| * modf:: Split fractional and integer parts |
| * nan:: Floating Not a Number |
| * nextafter:: Get next representable number |
| * pow:: X to the power Y |
| * remainder:: remainder of X divided by Y |
| * scalbn:: scalbn |
| * sin:: Sine or cosine (sin, cos) |
| * sinh:: Hyperbolic sine |
| * sqrt:: Positive square root |
| * tan:: Tangent |
| * tanh:: Hyperbolic tangent |
| @end menu |
| |
| @page |
| @node version |
| @section Version of library |
| |
| There are four different versions of the math library routines: IEEE, |
| POSIX, X/Open, or SVID. The version may be selected at runtime by |
| setting the global variable @code{_LIB_VERSION}, defined in |
| @file{math.h}. It may be set to one of the following constants defined |
| in @file{math.h}: @code{_IEEE_}, @code{_POSIX_}, @code{_XOPEN_}, or |
| @code{_SVID_}. The @code{_LIB_VERSION} variable is not specific to any |
| thread, and changing it will affect all threads. |
| |
| The versions of the library differ only in how errors are handled. |
| |
| In IEEE mode, the @code{matherr} function is never called, no warning |
| messages are printed, and @code{errno} is never set. |
| |
| In POSIX mode, @code{errno} is set correctly, but the @code{matherr} |
| function is never called and no warning messages are printed. |
| |
| In X/Open mode, @code{errno} is set correctly, and @code{matherr} is |
| called, but warning message are not printed. |
| |
| In SVID mode, functions which overflow return 3.40282346638528860e+38, |
| the maximum single-precision floating-point value, rather than infinity. |
| Also, @code{errno} is set correctly, @code{matherr} is called, and, if |
| @code{matherr} returns 0, warning messages are printed for some errors. |
| For example, by default @samp{log(-1.0)} writes this message on standard |
| error output: |
| |
| @example |
| log: DOMAIN error |
| @end example |
| |
| The library is set to X/Open mode by default. |
| |
| @page |
| @include mathfp/sacos.def |
| |
| @page |
| @include mathfp/eacosh.def |
| |
| @page |
| @include mathfp/sasine.def |
| |
| @page |
| @include mathfp/sasinh.def |
| |
| @page |
| @include mathfp/satan.def |
| |
| @page |
| @include mathfp/satan2.def |
| |
| @page |
| @include mathfp/eatanh.def |
| |
| @page |
| @include mathfp/wjn.def |
| |
| @page |
| @include common/scbrt.def |
| |
| @page |
| @include common/scopysign.def |
| |
| @page |
| @include mathfp/scosh.def |
| |
| @page |
| @include mathfp/serf.def |
| |
| @page |
| @include mathfp/sexp.def |
| |
| @page |
| @include common/sexpm1.def |
| |
| @page |
| @include mathfp/sfabs.def |
| |
| @page |
| @include mathfp/sfloor.def |
| |
| @page |
| @include mathfp/sfmod.def |
| |
| @page |
| @include mathfp/sfrexp.def |
| |
| @page |
| @include mathfp/erlgamma.def |
| |
| @page |
| @include mathfp/ehypot.def |
| |
| @page |
| @include common/silogb.def |
| |
| @page |
| @include common/sinfinity.def |
| |
| @page |
| @include common/sisnan.def |
| |
| @page |
| @include mathfp/sldexp.def |
| |
| @page |
| @include mathfp/slogarithm.def |
| |
| @page |
| @include mathfp/slog10.def |
| |
| @page |
| @include common/slog1p.def |
| |
| @page |
| @include common/smatherr.def |
| |
| @page |
| @include common/smodf.def |
| |
| @page |
| @include common/snan.def |
| |
| @page |
| @include common/snextafter.def |
| |
| @page |
| @include mathfp/spow.def |
| |
| @page |
| @include mathfp/eremainder.def |
| |
| @page |
| @include common/sscalbn.def |
| |
| @page |
| @include mathfp/ssqrt.def |
| |
| @page |
| @include mathfp/ssine.def |
| |
| @page |
| @include mathfp/ssineh.def |
| |
| @page |
| @include mathfp/stan.def |
| |
| @page |
| @include mathfp/stanh.def |