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Math::BigInt::Calc(3pm)               Perl Programmers Reference Guide               Math::BigInt::Calc(3pm)



NAME
       Math::BigInt::Calc - Pure Perl module to support Math::BigInt

SYNOPSIS
       Provides support for big integer calculations. Not intended to be used by other modules. Other
       modules which sport the same functions can also be used to support Math::BigInt, like
       Math::BigInt::GMP or Math::BigInt::Pari.

DESCRIPTION
       In order to allow for multiple big integer libraries, Math::BigInt was rewritten to use library
       modules for core math routines. Any module which follows the same API as this can be used instead by
       using the following:

               use Math::BigInt lib => 'libname';

       'libname' is either the long name ('Math::BigInt::Pari'), or only the short version like 'Pari'.

STORAGE
METHODS
       The following functions MUST be defined in order to support the use by Math::BigInt v1.70 or later:

               api_version()   return API version, 1 for v1.70, 2 for v1.83
               _new(string)    return ref to new object from ref to decimal string
               _zero()         return a new object with value 0
               _one()          return a new object with value 1
               _two()          return a new object with value 2
               _ten()          return a new object with value 10

               _str(obj)       return ref to a string representing the object
               _num(obj)       returns a Perl integer/floating point number
                               NOTE: because of Perl numeric notation defaults,
                               the _num'ified obj may lose accuracy due to
                               machine-dependent floating point size limitations

               _add(obj,obj)   Simple addition of two objects
               _mul(obj,obj)   Multiplication of two objects
               _div(obj,obj)   Division of the 1st object by the 2nd
                               In list context, returns (result,remainder).
                               NOTE: this is integer math, so no
                               fractional part will be returned.
                               The second operand will be not be 0, so no need to
                               check for that.
               _sub(obj,obj)   Simple subtraction of 1 object from another
                               a third, optional parameter indicates that the params
                               are swapped. In this case, the first param needs to
                               be preserved, while you can destroy the second.
                               sub (x,y,1) => return x - y and keep x intact!
               _dec(obj)       decrement object by one (input is guaranteed to be > 0)
               _inc(obj)       increment object by one


               _acmp(obj,obj)  <=> operator for objects (return -1, 0 or 1)

               _len(obj)       returns count of the decimal digits of the object
               _digit(obj,n)   returns the n'th decimal digit of object

               _is_one(obj)    return true if argument is 1
               _is_two(obj)    return true if argument is 2
               _is_ten(obj)    return true if argument is 10
               _is_zero(obj)   return true if argument is 0
               _is_even(obj)   return true if argument is even (0,2,4,6..)
               _is_odd(obj)    return true if argument is odd (1,3,5,7..)

               _copy           return a ref to a true copy of the object

               _check(obj)     check whether internal representation is still intact
                               return 0 for ok, otherwise error message as string

               _from_hex(str)  return new object from a hexadecimal string
               _from_bin(str)  return new object from a binary string
               _from_oct(str)  return new object from an octal string

               _as_hex(str)    return string containing the value as
                               unsigned hex string, with the '0x' prepended.
                               Leading zeros must be stripped.
               _as_bin(str)    Like as_hex, only as binary string containing only
                               zeros and ones. Leading zeros must be stripped and a
                               '0b' must be prepended.

               _rsft(obj,N,B)  shift object in base B by N 'digits' right
               _lsft(obj,N,B)  shift object in base B by N 'digits' left

               _xor(obj1,obj2) XOR (bit-wise) object 1 with object 2
                               Note: XOR, AND and OR pad with zeros if size mismatches
               _and(obj1,obj2) AND (bit-wise) object 1 with object 2
               _or(obj1,obj2)  OR (bit-wise) object 1 with object 2

               _mod(obj1,obj2) Return remainder of div of the 1st by the 2nd object
               _sqrt(obj)      return the square root of object (truncated to int)
               _root(obj)      return the n'th (n >= 3) root of obj (truncated to int)
               _fac(obj)       return factorial of object 1 (1*2*3*4..)
               _pow(obj1,obj2) return object 1 to the power of object 2
                               return undef for NaN
               _zeros(obj)     return number of trailing decimal zeros
               _modinv         return inverse modulus
               _modpow         return modulus of power ($x ** $y) % $z
               _log_int(X,N)   calculate integer log() of X in base N
                               X >= 0, N >= 0 (return undef for NaN)
                               returns (RESULT, EXACT) where EXACT is:
                                1     : result is exactly RESULT
                                0     : result was truncated to RESULT
                                undef : unknown whether result is exactly RESULT
               _gcd(obj,obj)   return Greatest Common Divisor of two objects

       The following functions are REQUIRED for an api_version of 2 or greater:

               _1ex($x)        create the number 1Ex where x >= 0
               _alen(obj)      returns approximate count of the decimal digits of the
                               object. This estimate MUST always be greater or equal
                               to what _len() returns.
               _nok(n,k)       calculate n over k (binomial coefficient)

       The following functions are optional, and can be defined if the underlying lib has a fast way to do
       them. If undefined, Math::BigInt will use pure Perl (hence slow) fallback routines to emulate these:

               _signed_or
               _signed_and
               _signed_xor

       Input strings come in as unsigned but with prefix (i.e. as '123', '0xabc' or '0b1101').

       So the library needs only to deal with unsigned big integers. Testing of input parameter validity is
       done by the caller, so you need not worry about underflow (f.i. in "_sub()", "_dec()") nor about
       division by zero or similar cases.

       The first parameter can be modified, that includes the possibility that you return a reference to a
       completely different object instead. Although keeping the reference and just changing its contents is
       preferred over creating and returning a different reference.

       Return values are always references to objects, strings, or true/false for comparison routines.

WRAP YOUR OWN
       If you want to port your own favourite c-lib for big numbers to the Math::BigInt interface, you can
       take any of the already existing modules as a rough guideline. You should really wrap up the latest
       BigInt and BigFloat testsuites with your module, and replace in them any of the following:

               use Math::BigInt;

       by this:

               use Math::BigInt lib => 'yourlib';

       This way you ensure that your library really works 100% within Math::BigInt.

LICENSE
       This program is free software; you may redistribute it and/or modify it under the same terms as Perl
       itself.

AUTHORS
       Original math code by Mark Biggar, rewritten by Tels <http://bloodgate.com/> in late 2000.  Seperated
       from BigInt and shaped API with the help of John Peacock.

       Fixed, speed-up, streamlined and enhanced by Tels 2001 - 2007.

SEE ALSO
       Math::BigInt, Math::BigFloat, Math::BigInt::GMP, Math::BigInt::FastCalc and Math::BigInt::Pari.



perl v5.12.5                                     2012-11-03                          Math::BigInt::Calc(3pm)