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# Math::BigRat

Perl 5 version 26.1 documentation

# NAME

Math::BigRat - Arbitrary big rational numbers

# SYNOPSIS

1. use Math::BigRat;
2. my \$x = Math::BigRat->new('3/7'); \$x += '5/9';
3. print \$x->bstr(), "\n";
4. print \$x ** 2, "\n";
5. my \$y = Math::BigRat->new('inf');
6. print "\$y ", (\$y->is_inf ? 'is' : 'is not'), " infinity\n";
7. my \$z = Math::BigRat->new(144); \$z->bsqrt();

# DESCRIPTION

Math::BigRat complements Math::BigInt and Math::BigFloat by providing support for arbitrary big rational numbers.

## MATH LIBRARY

You can change the underlying module that does the low-level math operations by using:

1. use Math::BigRat try => 'GMP';

Note: This needs Math::BigInt::GMP installed.

The following would first try to find Math::BigInt::Foo, then Math::BigInt::Bar, and when this also fails, revert to Math::BigInt::Calc:

1. use Math::BigRat try => 'Foo,Math::BigInt::Bar';

If you want to get warned when the fallback occurs, replace "try" with "lib":

1. use Math::BigRat lib => 'Foo,Math::BigInt::Bar';

If you want the code to die instead, replace "try" with "only":

1. use Math::BigRat only => 'Foo,Math::BigInt::Bar';

# METHODS

Any methods not listed here are derived from Math::BigFloat (or Math::BigInt), so make sure you check these two modules for further information.

• new()
1. \$x = Math::BigRat->new('1/3');

Create a new Math::BigRat object. Input can come in various forms:

1. \$x = Math::BigRat->new(123); # scalars
2. \$x = Math::BigRat->new('inf'); # infinity
3. \$x = Math::BigRat->new('123.3'); # float
4. \$x = Math::BigRat->new('1/3'); # simple string
5. \$x = Math::BigRat->new('1 / 3'); # spaced
6. \$x = Math::BigRat->new('1 / 0.1'); # w/ floats
7. \$x = Math::BigRat->new(Math::BigInt->new(3)); # BigInt
8. \$x = Math::BigRat->new(Math::BigFloat->new('3.1')); # BigFloat
9. \$x = Math::BigRat->new(Math::BigInt::Lite->new('2')); # BigLite
10. # You can also give D and N as different objects:
11. \$x = Math::BigRat->new(
12. Math::BigInt->new(-123),
13. Math::BigInt->new(7),
14. ); # => -123/7
• numerator()
1. \$n = \$x->numerator();

Returns a copy of the numerator (the part above the line) as signed BigInt.

• denominator()
1. \$d = \$x->denominator();

Returns a copy of the denominator (the part under the line) as positive BigInt.

• parts()
1. (\$n, \$d) = \$x->parts();

Return a list consisting of (signed) numerator and (unsigned) denominator as BigInts.

• numify()
1. my \$y = \$x->numify();

Returns the object as a scalar. This will lose some data if the object cannot be represented by a normal Perl scalar (integer or float), so use as_int() or as_float() instead.

This routine is automatically used whenever a scalar is required:

1. my \$x = Math::BigRat->new('3/1');
2. @array = (0, 1, 2, 3);
3. \$y = \$array[\$x]; # set \$y to 3
• as_int()/as_number()
1. \$x = Math::BigRat->new('13/7');
2. print \$x->as_int(), "\n"; # '1'

Returns a copy of the object as BigInt, truncated to an integer.

as_number() is an alias for as_int() .

• as_float()
1. \$x = Math::BigRat->new('13/7');
2. print \$x->as_float(), "\n"; # '1'
3. \$x = Math::BigRat->new('2/3');
4. print \$x->as_float(5), "\n"; # '0.66667'

Returns a copy of the object as BigFloat, preserving the accuracy as wanted, or the default of 40 digits.

This method was added in v0.22 of Math::BigRat (April 2008).

• as_hex()
1. \$x = Math::BigRat->new('13');
2. print \$x->as_hex(), "\n"; # '0xd'

Returns the BigRat as hexadecimal string. Works only for integers.

• as_bin()
1. \$x = Math::BigRat->new('13');
2. print \$x->as_bin(), "\n"; # '0x1101'

Returns the BigRat as binary string. Works only for integers.

• as_oct()
1. \$x = Math::BigRat->new('13');
2. print \$x->as_oct(), "\n"; # '015'

Returns the BigRat as octal string. Works only for integers.

• from_hex()
1. my \$h = Math::BigRat->from_hex('0x10');

Create a BigRat from a hexadecimal number in string form.

• from_oct()
1. my \$o = Math::BigRat->from_oct('020');

Create a BigRat from an octal number in string form.

• from_bin()
1. my \$b = Math::BigRat->from_bin('0b10000000');

Create a BigRat from an binary number in string form.

• bnan()
1. \$x = Math::BigRat->bnan();

Creates a new BigRat object representing NaN (Not A Number). If used on an object, it will set it to NaN:

1. \$x->bnan();
• bzero()
1. \$x = Math::BigRat->bzero();

Creates a new BigRat object representing zero. If used on an object, it will set it to zero:

1. \$x->bzero();
• binf()
1. \$x = Math::BigRat->binf(\$sign);

Creates a new BigRat object representing infinity. The optional argument is either '-' or '+', indicating whether you want infinity or minus infinity. If used on an object, it will set it to infinity:

1. \$x->binf();
2. \$x->binf('-');
• bone()
1. \$x = Math::BigRat->bone(\$sign);

Creates a new BigRat object representing one. The optional argument is either '-' or '+', indicating whether you want one or minus one. If used on an object, it will set it to one:

1. \$x->bone(); # +1
2. \$x->bone('-'); # -1
• length()
1. \$len = \$x->length();

Return the length of \$x in digits for integer values.

• digit()
1. print Math::BigRat->new('123/1')->digit(1); # 1
2. print Math::BigRat->new('123/1')->digit(-1); # 3

Return the N'ths digit from X when X is an integer value.

• bnorm()
1. \$x->bnorm();

Reduce the number to the shortest form. This routine is called automatically whenever it is needed.

• bfac()
1. \$x->bfac();

Calculates the factorial of \$x. For instance:

1. print Math::BigRat->new('3/1')->bfac(), "\n"; # 1*2*3
2. print Math::BigRat->new('5/1')->bfac(), "\n"; # 1*2*3*4*5

Works currently only for integers.

• bround()/round()/bfround()

Are not yet implemented.

• bmod()
1. \$x->bmod(\$y);

Returns \$x modulo \$y. When \$x is finite, and \$y is finite and non-zero, the result is identical to the remainder after floored division (F-division). If, in addition, both \$x and \$y are integers, the result is identical to the result from Perl's % operator.

• bmodinv()
1. \$x->bmodinv(\$mod); # modular multiplicative inverse

Returns the multiplicative inverse of \$x modulo \$mod . If

1. \$y = \$x -> copy() -> bmodinv(\$mod)

then \$y is the number closest to zero, and with the same sign as \$mod , satisfying

1. (\$x * \$y) % \$mod = 1 % \$mod

If \$x and \$y are non-zero, they must be relative primes, i.e., bgcd(\$y, \$mod)==1 . 'NaN ' is returned when no modular multiplicative inverse exists.

• bmodpow()
1. \$num->bmodpow(\$exp,\$mod); # modular exponentiation
2. # (\$num**\$exp % \$mod)

Returns the value of \$num taken to the power \$exp in the modulus \$mod using binary exponentiation. bmodpow is far superior to writing

1. \$num ** \$exp % \$mod

because it is much faster - it reduces internal variables into the modulus whenever possible, so it operates on smaller numbers.

bmodpow also supports negative exponents.

1. bmodpow(\$num, -1, \$mod)

is exactly equivalent to

1. bmodinv(\$num, \$mod)
• bneg()
1. \$x->bneg();

Used to negate the object in-place.

• is_one()
1. print "\$x is 1\n" if \$x->is_one();

Return true if \$x is exactly one, otherwise false.

• is_zero()
1. print "\$x is 0\n" if \$x->is_zero();

Return true if \$x is exactly zero, otherwise false.

• is_pos()/is_positive()
1. print "\$x is >= 0\n" if \$x->is_positive();

Return true if \$x is positive (greater than or equal to zero), otherwise false. Please note that '+inf' is also positive, while 'NaN' and '-inf' aren't.

is_positive() is an alias for is_pos() .

• is_neg()/is_negative()
1. print "\$x is < 0\n" if \$x->is_negative();

Return true if \$x is negative (smaller than zero), otherwise false. Please note that '-inf' is also negative, while 'NaN' and '+inf' aren't.

is_negative() is an alias for is_neg() .

• is_int()
1. print "\$x is an integer\n" if \$x->is_int();

Return true if \$x has a denominator of 1 (e.g. no fraction parts), otherwise false. Please note that '-inf', 'inf' and 'NaN' aren't integer.

• is_odd()
1. print "\$x is odd\n" if \$x->is_odd();

Return true if \$x is odd, otherwise false.

• is_even()
1. print "\$x is even\n" if \$x->is_even();

Return true if \$x is even, otherwise false.

• bceil()
1. \$x->bceil();

Set \$x to the next bigger integer value (e.g. truncate the number to integer and then increment it by one).

• bfloor()
1. \$x->bfloor();

Truncate \$x to an integer value.

• bint()
1. \$x->bint();

Round \$x towards zero.

• bsqrt()
1. \$x->bsqrt();

Calculate the square root of \$x.

• broot()
1. \$x->broot(\$n);

Calculate the N'th root of \$x.

Adds \$y to \$x and returns the result.

• bmul()
1. \$x->bmul(\$y);

Multiplies \$y to \$x and returns the result.

• bsub()
1. \$x->bsub(\$y);

Subtracts \$y from \$x and returns the result.

• bdiv()
1. \$q = \$x->bdiv(\$y);
2. (\$q, \$r) = \$x->bdiv(\$y);

In scalar context, divides \$x by \$y and returns the result. In list context, does floored division (F-division), returning an integer \$q and a remainder \$r so that \$x = \$q * \$y + \$r. The remainer (modulo) is equal to what is returned by \$x- bmod(\$y)>.

• bdec()
1. \$x->bdec();

Decrements \$x by 1 and returns the result.

• binc()
1. \$x->binc();

Increments \$x by 1 and returns the result.

• copy()
1. my \$z = \$x->copy();

Makes a deep copy of the object.

Please see the documentation in Math::BigInt for further details.

• bstr()/bsstr()
1. my \$x = Math::BigRat->new('8/4');
2. print \$x->bstr(), "\n"; # prints 1/2
3. print \$x->bsstr(), "\n"; # prints 1/2

Return a string representing this object.

• bcmp()
1. \$x->bcmp(\$y);

Compares \$x with \$y and takes the sign into account. Returns -1, 0, 1 or undef.

• bacmp()
1. \$x->bacmp(\$y);

Compares \$x with \$y while ignoring their sign. Returns -1, 0, 1 or undef.

• beq()
1. \$x -> beq(\$y);

Returns true if and only if \$x is equal to \$y, and false otherwise.

• bne()
1. \$x -> bne(\$y);

Returns true if and only if \$x is not equal to \$y, and false otherwise.

• blt()
1. \$x -> blt(\$y);

Returns true if and only if \$x is equal to \$y, and false otherwise.

• ble()
1. \$x -> ble(\$y);

Returns true if and only if \$x is less than or equal to \$y, and false otherwise.

• bgt()
1. \$x -> bgt(\$y);

Returns true if and only if \$x is greater than \$y, and false otherwise.

• bge()
1. \$x -> bge(\$y);

Returns true if and only if \$x is greater than or equal to \$y, and false otherwise.

• blsft()/brsft()

Used to shift numbers left/right.

Please see the documentation in Math::BigInt for further details.

• band()
1. \$x->band(\$y); # bitwise and
• bior()
1. \$x->bior(\$y); # bitwise inclusive or
• bxor()
1. \$x->bxor(\$y); # bitwise exclusive or
• bnot()
1. \$x->bnot(); # bitwise not (two's complement)
• bpow()
1. \$x->bpow(\$y);

Compute \$x ** \$y.

Please see the documentation in Math::BigInt for further details.

• blog()
1. \$x->blog(\$base, \$accuracy); # logarithm of x to the base \$base

If \$base is not defined, Euler's number (e) is used:

1. print \$x->blog(undef, 100); # log(x) to 100 digits
• bexp()
1. \$x->bexp(\$accuracy); # calculate e ** X

Calculates two integers A and B so that A/B is equal to e ** \$x , where e is Euler's number.

This method was added in v0.20 of Math::BigRat (May 2007).

• bnok()
1. \$x->bnok(\$y); # x over y (binomial coefficient n over k)

Calculates the binomial coefficient n over k, also called the "choose" function. The result is equivalent to:

1. ( n ) n!
2. | - | = -------
3. ( k ) k!(n-k)!

This method was added in v0.20 of Math::BigRat (May 2007).

• config()
1. use Data::Dumper;
2. print Dumper ( Math::BigRat->config() );
3. print Math::BigRat->config()->{lib}, "\n";

Returns a hash containing the configuration, e.g. the version number, lib loaded etc. The following hash keys are currently filled in with the appropriate information.

1. key RO/RW Description
2. Example
3. ============================================================
4. lib RO Name of the Math library
5. Math::BigInt::Calc
6. lib_version RO Version of 'lib'
7. 0.30
8. class RO The class of config you just called
9. Math::BigRat
10. version RO version number of the class you used
11. 0.10
13. undef
15. undef
16. precision RW Global precision
17. undef
18. accuracy RW Global accuracy
19. undef
20. round_mode RW Global round mode
21. even
22. div_scale RW Fallback accuracy for div
23. 40
24. trap_nan RW Trap creation of NaN (undef = no)
25. undef
26. trap_inf RW Trap creation of +inf/-inf (undef = no)
27. undef

By passing a reference to a hash you may set the configuration values. This works only for values that a marked with a RW above, anything else is read-only.

# BUGS

Please report any bugs or feature requests to bug-math-bigrat at rt.cpan.org , or through the web interface at https://rt.cpan.org/Ticket/Create.html?Queue=Math-BigRat (requires login). We will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

# SUPPORT

You can find documentation for this module with the perldoc command.

1. perldoc Math::BigRat

You can also look for information at: