math::bignum - Arbitrary precision integer numbers
package require Tcl ?8.4?
package require math::bignum ?3.1?
::math::bignum::fromstr string ?radix?
::math::bignum::tostr bignum ?radix?
::math::bignum::sign bignum
::math::bignum::abs bignum
::math::bignum::cmp a b
::math::bignum::iszero bignum
::math::bignum::lt a b
::math::bignum::le a b
::math::bignum::gt a b
::math::bignum::ge a b
::math::bignum::eq a b
::math::bignum::ne a b
::math::bignum::isodd bignum
::math::bignum::iseven bignum
::math::bignum::add a b
::math::bignum::sub a b
::math::bignum::mul a b
::math::bignum::divqr a b
::math::bignum::div a b
::math::bignum::rem a b
::math::bignum::mod n m
::math::bignum::pow base exp
::math::bignum::powm base exp m
::math::bignum::sqrt bignum
::math::bignum::rand bits
::math::bignum::lshift bignum bits
::math::bignum::rshift bignum bits
::math::bignum::bitand a b
::math::bignum::bitor a b
::math::bignum::bitxor a b
::math::bignum::setbit bignumVar bit
::math::bignum::clearbit bignumVar bit
::math::bignum::testbit bignum bit
::math::bignum::bits bignum
The bignum package provides arbitrary precision integer math (also
known as "big numbers") capabilities to the Tcl language. Big
numbers are internally represented at Tcl lists: this package provides a set
of procedures operating against the internal representation in order to:
- perform math operations
- convert bignums from the internal representation to a string in the
desired radix and vice versa.
But the two constants "0" and "1" are
automatically converted to the internal representation, in order to easily
compare a number to zero, or increment a big number.
The bignum interface is opaque, so operations on bignums that are
not returned by procedures in this package (but created by hand) may lead to
unspecified behaviours. It's safe to treat bignums as pure values, so there
is no need to free a bignum, or to duplicate it via a special operation.
This section shows some simple example. This library being just a
way to perform math operations, examples may be the simplest way to learn
how to work with it. Consult the API section of this man page for
information about individual procedures.
package require math::bignum
# Multiplication of two bignums
set a [::math::bignum::fromstr 88888881111111]
set b [::math::bignum::fromstr 22222220000000]
set c [::math::bignum::mul $a $b]
puts [::math::bignum::tostr $c] ; # => will output 1975308271604953086420000000
set c [::math::bignum::sqrt $c]
puts [::math::bignum::tostr $c] ; # => will output 44444440277777
# From/To string conversion in different radix
set a [::math::bignum::fromstr 1100010101010111001001111010111 2]
puts [::math::bignum::tostr $a 16] ; # => will output 62ab93d7
# Factorial example
proc fact n {
# fromstr is not needed for 0 and 1
set z 1
for {set i 2} {$i <= $n} {incr i} {
set z [::math::bignum::mul $z [::math::bignum::fromstr $i]]
}
return $z
}
puts [::math::bignum::tostr [fact 100]]
- ::math::bignum::fromstr string ?radix?
- Convert string into a bignum. If radix is omitted or zero,
the string is interpreted in hex if prefixed with 0x, in octal if
prefixed with ox, in binary if it's pefixed with bx, as a
number in radix 10 otherwise. If instead the radix argument is
specified in the range 2-36, the string is interpreted in the given
radix. Please note that this conversion is not needed for two constants :
0 and 1. (see the example)
- ::math::bignum::tostr bignum ?radix?
- Convert bignum into a string representing the number in the
specified radix. If radix is omitted, the default is 10.
- ::math::bignum::sign bignum
- Return the sign of the bignum. The procedure returns 0 if the number is
positive, 1 if it's negative.
- ::math::bignum::abs bignum
- Return the absolute value of the bignum.
- ::math::bignum::cmp a b
- Compare the two bignums a and b, returning 0 if a == b,
1 if a > b, and -1 if a < b.
- ::math::bignum::iszero bignum
- Return true if bignum value is zero, otherwise false is
returned.
- ::math::bignum::lt a b
- Return true if a < b, otherwise false is returned.
- ::math::bignum::le a b
- Return true if a <= b, otherwise false is returned.
- ::math::bignum::gt a b
- Return true if a > b, otherwise false is returned.
- ::math::bignum::ge a b
- Return true if a >= b, otherwise false is returned.
- ::math::bignum::eq a b
- Return true if a == b, otherwise false is returned.
- ::math::bignum::ne a b
- Return true if a != b, otherwise false is returned.
- ::math::bignum::isodd bignum
- Return true if bignum is odd.
- ::math::bignum::iseven bignum
- Return true if bignum is even.
- ::math::bignum::add a b
- Return the sum of the two bignums a and b.
- ::math::bignum::sub a b
- Return the difference of the two bignums a and b.
- ::math::bignum::mul a b
- Return the product of the two bignums a and b. The
implementation uses Karatsuba multiplication if both the numbers are
bigger than a given threshold, otherwise the direct algorith is used.
- ::math::bignum::divqr a b
- Return a two-elements list containing as first element the quotient of the
division between the two bignums a and b, and the remainder
of the division as second element.
- ::math::bignum::div a b
- Return the quotient of the division between the two bignums a and
b.
- ::math::bignum::rem a b
- Return the remainder of the division between the two bignums a and
b.
- ::math::bignum::mod n m
- Return n modulo m. This operation is called modular
reduction.
- ::math::bignum::pow base exp
- Return base raised to the exponent exp.
- ::math::bignum::powm base exp m
- Return base raised to the exponent exp, modulo m.
This function is often used in the field of cryptography.
- ::math::bignum::sqrt bignum
- Return the integer part of the square root of bignum
- ::math::bignum::rand bits
- Return a random number of at most bits bits. The returned number is
internally generated using Tcl's expr rand() function and is not
suitable where an unguessable and cryptographically secure random number
is needed.
- ::math::bignum::lshift bignum bits
- Return the result of left shifting bignum's binary representation
of bits positions on the left. This is equivalent to multiplying by
2^bits but much faster.
- ::math::bignum::rshift bignum bits
- Return the result of right shifting bignum's binary representation
of bits positions on the right. This is equivalent to dividing by
2^bits but much faster.
- ::math::bignum::bitand a b
- Return the result of doing a bitwise AND operation on a and b. The
operation is restricted to positive numbers, including zero. When negative
numbers are provided as arguments the result is undefined.
- ::math::bignum::bitor a b
- Return the result of doing a bitwise OR operation on a and b. The
operation is restricted to positive numbers, including zero. When negative
numbers are provided as arguments the result is undefined.
- ::math::bignum::bitxor a b
- Return the result of doing a bitwise XOR operation on a and b. The
operation is restricted to positive numbers, including zero. When negative
numbers are provided as arguments the result is undefined.
- ::math::bignum::setbit bignumVar bit
- Set the bit at bit position to 1 in the bignum stored in the
variable bignumVar. Bit 0 is the least significant.
- ::math::bignum::clearbit bignumVar bit
- Set the bit at bit position to 0 in the bignum stored in the
variable bignumVar. Bit 0 is the least significant.
- ::math::bignum::testbit bignum bit
- Return true if the bit at the bit position of bignum is on,
otherwise false is returned. If bit is out of range, it is
considered as set to zero.
- ::math::bignum::bits bignum
- Return the number of bits needed to represent bignum in radix 2.
This document, and the package it describes, will undoubtedly
contain bugs and other problems. Please report such in the category math
:: bignum of the Tcllib SF Trackers
[http://sourceforge.net/tracker/?group_id=12883]. Please also report any
ideas for enhancements you may have for either package and/or
documentation.
bignums, math, multiprecision, tcl
Copyright (c) 2004 Salvatore Sanfilippo <antirez at invece dot org>
Copyright (c) 2004 Arjen Markus <arjenmarkus at users dot sourceforge dot net>