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Operations on arbitrary-precision integers.
Big integers (type big_int or equivalently Big_int.t) are signed integers of arbitrary size. This module lets you compute with huge numbers, whose size is limited only by the amount of memory given to OCaml. The downside is speed, as big integers are much slower than any other type of integer known to OCaml.
sqrt_big_int a returns the integer square root of a, that is, the largest big integer r such that r * r <= a.
raisesInvalid_argument
if a is negative.
Euclidean division of two big integers. The first part of the result is the quotient, the second part is the remainder. Writing (q,r) = quomod_big_int a b, we have a = q * b + r and 0 <= r < |b|.
Exponentiation functions. Return the big integer representing the first argument a raised to the power b (the second argument). Depending on the function, a and b can be either small integers or big integers.
Return the number of significant bits in the absolute value of the given big integer. num_bits_big_int a returns 0 if a is 0; otherwise it returns a positive integer n such that 2^(n-1) <= |a| < 2^n.
Convert a string to a big integer, in decimal. The string consists of an optional - or + sign, followed by one or several decimal digits.
val big_int_of_string_opt : string ->big_int option
Convert a string to a big integer, in decimal. The string consists of an optional - or + sign, followed by one or several decimal digits.
Convert a string to a big integer, in decimal. The string consists of an optional - or + sign, followed by one or several decimal digits. Other the function returns None.
to_string_in_base b n returns the string representation in base b of the given big integer n. Should you have advanced needs (arbitrarily large bases, or custom digits instead of the usual 0,1,...9,a,b,...,z), use to_string_in_custom_base instead.
raisesInvalid_argument
if b is not in 2 .. 36.
val to_string_in_custom_base : string ->int ->big_int-> string
First argument, called symbols, is the vector of the symbols used to represent the digits in base b. to_string_in_base is almost equivalent to to_string_in_custom_base big_int_base_default_symbols, the difference being that to_string_in_custom_base allows the base to be arbitrarily large, provided that symbols can accommodate it. Concretely, the base b must be at least 2, and symbols must be of size at least b. The default value of big_int_base_default_symbols contains 62 symbols, as it uses lowercase and uppercase letters both. See below for more information.
raisesInvalid_argument
if b is incorrect.
val big_int_base_default_symbols : string
Default vector of symbols used by to_string_in_base and its fixed-base derivatives to_string_in_binary, to_string_in_octal and to_string_in_hexa to represent digits. The symbol at position p encodes the value p. The original value of this vector is, schematically, ['0'..'9' 'a' 'b'..'z' 'A'
'B'..'Z'], which is sufficient for bases up to and including 62. The basic to_string_in_base function is capped to base 36 to avoid unexpected behaviours do to the case-sensitivity of the output in bases 37 to 62. You technically can mutate the vector, for instance if you prefer to exchange lower- and upper-case symbols program-wide. As usual where mutability is concerned, discretion is advised. Most of the time, it is better to build custom functions using to_string_in_custom_base.
Test whether the given big integer is small enough to be representable as a small integer (type int) without loss of precision. On a 32-bit platform, is_int_big_int a returns true if and only if a is between -230 and 230-1. On a 64-bit platform, is_int_big_int a returns true if and only if a is between -262 and 262-1.
shift_left_big_int b n returns b shifted left by n bits. Equivalent to multiplication by 2^n.
shift_right_big_int b n returns b shifted right by n bits. Equivalent to division by 2^n with the result being rounded towards minus infinity.
val shift_right_towards_zero_big_int : big_int->int ->big_int
shift_right_big_int b n returns b shifted right by n bits. Equivalent to division by 2^n with the result being rounded towards minus infinity.
shift_right_towards_zero_big_int b n returns b shifted right by n bits. The shift is performed on the absolute value of b, and the result has the same sign as b. Equivalent to division by 2^n with the result being rounded towards zero.
shift_right_towards_zero_big_int b n returns b shifted right by n bits. The shift is performed on the absolute value of b, and the result has the same sign as b. Equivalent to division by 2^n with the result being rounded towards zero.
extract_big_int bi ofs n returns a nonnegative number corresponding to bits ofs to ofs + n - 1 of the binary representation of bi. If bi is negative, a two's complement representation is used.