Sisyphus > Math-LongDouble > Math::LongDouble

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Module Version: 0.04   Source  

NAME ^

Math::LongDouble - perl interface to C's long double operations (for perls that don't already have that capability)

BUGS ^

  This module has bugs on perls built with a Microsoft compiler (eg
  ActivePerl) - even if the binaries installed onto the MSVC-built
  perl were built using MinGW on a MinGW-built perl such as Strawberry
  Perl (where no such problem exists).
  By some means that is still unclear, the 'long double' precision
  can apparently be reduced to 'double' precision whenever a 
  Math::LongDouble object is raised to a power (or a square root taken)
  on MSVC-built perls.
  This bug manifests itself in causing some test failures in t/cmp.t
  and t/pow.t.

DESCRIPTION ^

  If your perl's NV is a 'long double', then there's no point in using this
  module. But if your perl's NV is a 'double', then this module provides
  you with a way of performing arithmetic operations with long double
  precision.

   use Math::LongDouble qw(:all);

   my $arg = 32.1;
   my $ld1 = Math::LongDouble->new($arg);# Stringify $arg, then assign 
                                          # using C's strtold()
   my $ld2 = NVtoLD($arg); # Assign the NV 32.1 to $ld2.

OVERLOADING ^

   The following operations are overloaded:
    + - * / **
    += -= *= /= **=
    != == <= >= <=> < >
    ++ --
    =
    abs bool ! int print
    sqrt log exp
    sin cos atan2

    Arguments to the overloaded operations must be Math::LongDouble
    objects.

     $ld = $ld + 3.1; # currently an error. Do instead:

     $ld = $ld + Math::LongDouble->new('3.1');

ASSIGNMENT FUNCTIONS ^

   The following create and assign a new Math::LongDouble.

    $ld = Math::LongDouble->new($arg);
     Returns a Math::LongDouble object to which the numeric value of $arg
     has been assigned.
     If no arg is supplied then $ld will be NaN.

    $ld = UVtoLD($arg);
     Returns a Math::LongDouble object to which the numeric (unsigned
     integer) value of $arg has been assigned.

    $ld = IVtoLD($arg);
     Returns a Math::LongDouble object to which the numeric (signed
     integer) value of $arg has been assigned.

    $ld = NVtoLD($arg);
     Returns a Math::LongDouble object to which the numeric (floating
     point) value of $arg has been assigned.

    $ld2 = LDtoLD($ld1);
     Returns a Math::LongDouble object that is a copy of the
     Math::LongDouble object provided as the argument.
     Courtesy of overloading, this is in effect no different to doing:
     $ld2 = $ld1;

    $ld = STRtoLD($str);
     Returns a Math::LongDouble object that has the value of the string
     $str.

ASSIGNMENT OF INF, NAN, UNITY and ZERO ^

   $ld = InfLD($sign);
    If $sign < 0, returns a Math::LongDouble object set to
    negative infinity; else returns a Math::LongDouble object set
    to positive infinity.

   $ld = NaNLD($sign);
    If $sign < 0, returns a Math::longDouble object set to
    negative NaN; else returns a Math::LongDouble object set to
    positive NaN. It may be problematical as to whether a NaN
    with the correct sign has been returned ... but, either way,
    it should return a NaN.

   $ld = ZeroLD($sign);
    If $sign < 0, returns a Math::LongDouble object set to
    negative zero; else returns a Math::LongDouble object set to 
    zero.

   $ld = UnityLD($sign);
    If $sign < 0, returns a Math::LongDouble object set to
    negative one; else returns a Math::LongDouble object set to 
    one.

   ld_set_prec($precision);
    Sets the precision of stringified values to $precision decimal
    digits.

   $precision = ld_get_prec();
    Returns the precision (in decimal digits) that will be used
    when stringifying values (by printing them, or calling
    LDtoSTR).

RETRIEVAL FUNCTIONS ^

   The following functions provide ways of seeing the value of
   Math::LongDouble objects.

   $nv = LDtoNV($ld);
    This function returns the value of the Math::LongDouble object to
    a perl scalar (NV). It may not translate the value accurately.

   $string = LDtoSTR($ld);
    Returns the value of the Math::LongDouble object as a string.
    The returned string will contain the same as is displayed by
    "print $ld", except that print() will strip the trailing zeroes
    in the mantissa (significand) whereas LDtoSTR won't.
    By default, provides 18 decimal digits of precision. This can be
    altered by specifying the desired precision (in decimal digits)
    in a call to ld_set_prec.

   $string = LDtoSTRP($ld, $precision);
    Same as LDtoSTR, but takes an additional arg that specifies the
    precision (in decimal digits) of the stringified return value.

OTHER FUNCTIONS ^

   $bool = is_NaNLD($ld); 
    Returns 1 if $ld is a Math::LongDouble NaN.
    Else returns 0

   $int = is_InfLD($ld)
    If the Math::LongDouble object $ld is -inf, returns -1.
    If it is +inf, returns 1.
    Otherwise returns 0.

   $int = is_ZeroLD($ld);
    If the Math::LongDouble object $ld is -0, returns -1.
    If it is zero, returns 1.
    Otherwise returns 0.

   $int = cmp_NV($ld, $nv);
    $nv can be any perl number - ie NV, UV or IV.
    If the Math::LongDouble object $ld < $nv returns -1.
    If it is > $nv, returns 1.
    Otherwise returns 0.

LICENSE ^

   This program is free software; you may redistribute it and/or modify
   it under the same terms as Perl itself.
   Copyright 2012, 2013 Sisyphus

AUTHOR ^

   Sisyphus <sisyphus at(@) cpan dot (.) org>
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