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RedHat 9 (Linux i386) - man page for math::bigint::calc (redhat section 3pm)

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
       (except Math::BigInt::Cached). Other modules which sport the same functions can also be
       used to support Math::Bigint, like 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'.

EXPORT
       The following functions MUST be defined in order to support the use by Math::BigInt:

	       _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

	       _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-dependend 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.
	       _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 garant. 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_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

       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 rou-
       tines to emulate these:

	       _from_hex(str)  return ref to new object from ref to hexadecimal string
	       _from_bin(str)  return ref to new object from ref to binary string

	       _as_hex(str)    return ref to scalar 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
			       For unsupported bases B, return undef to signal failure
	       _lsft(obj,N,B)  shift object in base B by N 'digits' left
			       For unsupported bases B, return undef to signal failure

	       _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(obj,obj)   Return remainder of div of the 1st by the 2nd object
	       _sqrt(obj)      return the square root of object (truncate to int)
	       _fac(obj)       return factorial of object 1 (1*2*3*4..)
	       _pow(obj,obj)   return object 1 to the power of object 2
	       _gcd(obj,obj)   return Greatest Common Divisor of two objects

	       _zeros(obj)     return number of trailing decimal zeros
	       _modinv	       return inverse modulus
	       _modpow	       return modulus of power ($x ** $y) % $z

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

       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 ref-
       erence to a completely different object instead. Although keeping the reference and just
       changing it's contents is prefered over creating and returning a different reference.

       Return values are always references to objects or strings. Exceptions are "_lsft()" and
       "_rsft()", which return undef if they can not shift the argument. This is used to delegate
       shifting of bases different than the one you can support back to Math::BigInt, which will
       use some generic code to calculate the result.

WRAP YOUR OWN
       If you want to port your own favourite c-lib for big numbers to the Math::BigInt inter-
       face, 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,
       2001.  Seperated from BigInt and shaped API with the help of John Peacock.

SEE ALSO
       Math::BigInt, Math::BigFloat, Math::BigInt::BitVect, Math::BigInt::GMP, Math::Big-
       Int::Cached and Math::BigInt::Pari.

perl v5.8.0				    2002-06-01			  Math::BigInt::Calc(3pm)


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