This is gmp.info, produced by makeinfo version 4.0 from gmp.texi.

INFO-DIR-SECTION GNU libraries
START-INFO-DIR-ENTRY
* gmp: (gmp).                   GNU Multiple Precision Arithmetic Library.
END-INFO-DIR-ENTRY


File: gmp.info,  Node: I/O of Integers,  Next: Integer Random Numbers,  Prev: Integer Logic and Bit Fiddling,  Up: Integer Functions

Input and Output Functions
==========================

   Functions that perform input from a stdio stream, and functions that
output to a stdio stream.  Passing a `NULL' pointer for a STREAM
argument to any of these functions will make them read from `stdin' and
write to `stdout', respectively.

   When using any of these functions, it is a good idea to include
`stdio.h' before `gmp.h', since that will allow `gmp.h' to define
prototypes for these functions.

 - Function: size_t mpz_out_str (FILE *STREAM, int BASE, mpz_t OP)
     Output OP on stdio stream STREAM, as a string of digits in base
     BASE.  The base may vary from 2 to 36.

     Return the number of bytes written, or if an error occurred,
     return 0.

 - Function: size_t mpz_inp_str (mpz_t ROP, FILE *STREAM, int BASE)
     Input a possibly white-space preceded string in base BASE from
     stdio stream STREAM, and put the read integer in ROP.  The base
     may vary from 2 to 36.  If BASE is 0, the actual base is
     determined from the leading characters: if the first two
     characters are `0x' or `0X', hexadecimal is assumed, otherwise if
     the first character is `0', octal is assumed, otherwise decimal is
     assumed.

     Return the number of bytes read, or if an error occurred, return 0.

 - Function: size_t mpz_out_raw (FILE *STREAM, mpz_t OP)
     Output OP on stdio stream STREAM, in raw binary format.  The
     integer is written in a portable format, with 4 bytes of size
     information, and that many bytes of limbs.  Both the size and the
     limbs are written in decreasing significance order (i.e., in
     big-endian).

     The output can be read with `mpz_inp_raw'.

     Return the number of bytes written, or if an error occurred,
     return 0.

     The output of this can not be read by `mpz_inp_raw' from GMP 1,
     because of changes necessary for compatibility between 32-bit and
     64-bit machines.

 - Function: size_t mpz_inp_raw (mpz_t ROP, FILE *STREAM)
     Input from stdio stream STREAM in the format written by
     `mpz_out_raw', and put the result in ROP.  Return the number of
     bytes read, or if an error occurred, return 0.

     This routine can read the output from `mpz_out_raw' also from GMP
     1, in spite of changes necessary for compatibility between 32-bit
     and 64-bit machines.


File: gmp.info,  Node: Integer Random Numbers,  Next: Miscellaneous Integer Functions,  Prev: I/O of Integers,  Up: Integer Functions

Random Number Functions
=======================

   The random number functions of GMP come in two groups; older function
that rely on a global state, and newer functions that accept a state
parameter that is read and modified.  Please see the *Note Random
Number Functions:: for more information on how to use and not to use
random number functions.

 - Function: void mpz_urandomb (mpz_t ROP, gmp_randstate_t STATE,
          unsigned long int N)
     Generate a uniformly distributed random integer in the range 0 to
     2^N-1, inclusive.

     The variable STATE must be initialized by calling one of the
     `gmp_randinit' functions (*Note Random State Initialization::)
     before invoking this function.

 - Function: void mpz_urandomm (mpz_t ROP, gmp_randstate_t STATE, mpz_t
          N)
     Generate a uniform random integer in the range 0 to N-1, inclusive.

     The variable STATE must be initialized by calling one of the
     `gmp_randinit' functions (*Note Random State Initialization::)
     before invoking this function.

 - Function: void mpz_rrandomb (mpz_t ROP, gmp_randstate_t STATE,
          unsigned long int N)
     Generate a random integer with long strings of zeros and ones in
     the binary representation.  Useful for testing functions and
     algorithms, since this kind of random numbers have proven to be
     more likely to trigger corner-case bugs.  The random number will
     be in the range 0 to 2^N-1, inclusive.

     The variable STATE must be initialized by calling one of the
     `gmp_randinit' functions (*Note Random State Initialization::)
     before invoking this function.

 - Function: void mpz_random (mpz_t ROP, mp_size_t MAX_SIZE)
     Generate a random integer of at most MAX_SIZE limbs.  The generated
     random number doesn't satisfy any particular requirements of
     randomness.  Negative random numbers are generated when MAX_SIZE
     is negative.

     This function is obsolete.  Use `mpz_urandomb' or `mpz_urandomm'
     instead.

 - Function: void mpz_random2 (mpz_t ROP, mp_size_t MAX_SIZE)
     Generate a random integer of at most MAX_SIZE limbs, with long
     strings of zeros and ones in the binary representation.  Useful
     for testing functions and algorithms, since this kind of random
     numbers have proven to be more likely to trigger corner-case bugs.
     Negative random numbers are generated when MAX_SIZE is negative.

     This function is obsolete.  Use `mpz_rrandomb' instead.


File: gmp.info,  Node: Miscellaneous Integer Functions,  Prev: Integer Random Numbers,  Up: Integer Functions

Miscellaneous Functions
=======================

 - Function: int mpz_fits_ulong_p (mpz_t OP)
 - Function: int mpz_fits_slong_p (mpz_t OP)
 - Function: int mpz_fits_uint_p (mpz_t OP)
 - Function: int mpz_fits_sint_p (mpz_t OP)
 - Function: int mpz_fits_ushort_p (mpz_t OP)
 - Function: int mpz_fits_sshort_p (mpz_t OP)
     Return non-zero iff the value of OP fits in an `unsigned long int',
     `signed long int', `unsigned int', `signed int', `unsigned short
     int', or `signed short int', respectively.  Otherwise, return zero.

 - Macro: int mpz_odd_p (mpz_t OP)
 - Macro: int mpz_even_p (mpz_t OP)
     Determine whether OP is odd or even, respectively.  Return
     non-zero if yes, zero if no.  These macros evaluate their argument
     more than once.

 - Function: size_t mpz_size (mpz_t OP)
     Return the size of OP measured in number of limbs.  If OP is zero,
     the returned value will be zero.

 - Function: size_t mpz_sizeinbase (mpz_t OP, int BASE)
     Return the size of OP measured in number of digits in base BASE.
     The base may vary from 2 to 36.  The sign of OP is ignored, just
     the absolute value is used.  The returned value will be exact or 1
     too big.  If BASE is a power of 2, the returned value will always
     be exact.

     This function is useful in order to allocate the right amount of
     space before converting OP to a string.  The right amount of
     allocation is normally two more than the value returned by
     `mpz_sizeinbase' (one extra for a minus sign and one for the
     null-terminator).


File: gmp.info,  Node: Rational Number Functions,  Next: Floating-point Functions,  Prev: Integer Functions,  Up: Top

Rational Number Functions
*************************

   This chapter describes the GMP functions for performing arithmetic
on rational numbers.  These functions start with the prefix `mpq_'.

   Rational numbers are stored in objects of type `mpq_t'.

   All rational arithmetic functions assume operands have a canonical
form, and canonicalize their result.  The canonical from means that the
denominator and the numerator have no common factors, and that the
denominator is positive.  Zero has the unique representation 0/1.

   Pure assignment functions do not canonicalize the assigned variable.
It is the responsibility of the user to canonicalize the assigned
variable before any arithmetic operations are performed on that
variable.

 - Function: void mpq_canonicalize (mpq_t OP)
     Remove any factors that are common to the numerator and
     denominator of OP, and make the denominator positive.

* Menu:

* Initializing Rationals::
* Rational Conversions::
* Rational Arithmetic::
* Comparing Rationals::
* Applying Integer Functions::
* I/O of Rationals::


File: gmp.info,  Node: Initializing Rationals,  Next: Rational Conversions,  Prev: Rational Number Functions,  Up: Rational Number Functions

Initialization and Assignment Functions
=======================================

 - Function: void mpq_init (mpq_t DEST_RATIONAL)
     Initialize DEST_RATIONAL and set it to 0/1.  Each variable should
     normally only be initialized once, or at least cleared out (using
     the function `mpq_clear') between each initialization.

 - Function: void mpq_clear (mpq_t RATIONAL_NUMBER)
     Free the space occupied by RATIONAL_NUMBER.  Make sure to call this
     function for all `mpq_t' variables when you are done with them.

 - Function: void mpq_set (mpq_t ROP, mpq_t OP)
 - Function: void mpq_set_z (mpq_t ROP, mpz_t OP)
     Assign ROP from OP.

 - Function: void mpq_set_ui (mpq_t ROP, unsigned long int OP1,
          unsigned long int OP2)
 - Function: void mpq_set_si (mpq_t ROP, signed long int OP1, unsigned
          long int OP2)
     Set the value of ROP to OP1/OP2.  Note that if OP1 and OP2 have
     common factors, ROP has to be passed to `mpq_canonicalize' before
     any operations are performed on ROP.

 - Function: int mpq_set_str (mpq_t ROP, char *STR, int BASE)
     Set ROP from a null-terminated string STR in the given BASE.

     The string can be an integer like "41" or a fraction like
     "41/152".  The fraction must be in canonical form (*note Rational
     Number Functions::), or if not then `mpq_canonicalize' must be
     called.

     The numerator and optional denominator are parsed the same as in
     `mpz_set_str' (*note Assigning Integers::).  White space is
     allowed in the string, and is simply ignored.  The BASE can vary
     from 2 to 36, or if BASE is 0 then the leading characters are
     used: `0x' for hex, `0' for octal, or decimal otherwise.  Note
     that this is done separately for the numerator and denominator, so
     for instance `0xEF/100' is 239/100, whereas `0xEF/0x100' is
     239/256.

     The return value is 0 if the entire string is a valid number, or
     -1 if not.

 - Function: void mpq_swap (mpq_t ROP1, mpq_t ROP2)
     Swap the values ROP1 and ROP2 efficiently.


File: gmp.info,  Node: Rational Conversions,  Next: Rational Arithmetic,  Prev: Initializing Rationals,  Up: Rational Number Functions

Conversion Functions
====================

 - Function: double mpq_get_d (mpq_t OP)
     Convert OP to a `double'.

 - Function: void mpq_set_d (mpq_t ROP, double OP)
 - Function: void mpq_set_f (mpq_t ROP, mpf_t OP)
     Set ROP to the value of OP, without rounding.

 - Function: char * mpq_get_str (char *STR, int BASE, mpq_t OP)
     Convert OP to a string of digits in base BASE.  The base may vary
     from 2 to 36.  The string will be of the form `num/den', or if the
     denominator is 1 then just `num'.

     If STR is `NULL', the result string is allocated using the current
     allocation function (*note Custom Allocation::).  The block will be
     `strlen(str)+1' bytes, that being exactly enough for the string and
     null-terminator.

     If STR is not `NULL', it should point to a block of storage large
     enough for the result, that being

          mpz_sizeinbase (mpq_numref(OP), BASE)
          + mpz_sizeinbase (mpq_denref(OP), BASE) + 3

     The three extra bytes are for a possible minus sign, possible
     slash, and the null-terminator.

     A pointer to the result string is returned, being either the
     allocated block, or the given STR.


File: gmp.info,  Node: Rational Arithmetic,  Next: Comparing Rationals,  Prev: Rational Conversions,  Up: Rational Number Functions

Arithmetic Functions
====================

 - Function: void mpq_add (mpq_t SUM, mpq_t ADDEND1, mpq_t ADDEND2)
     Set SUM to ADDEND1 + ADDEND2.

 - Function: void mpq_sub (mpq_t DIFFERENCE, mpq_t MINUEND, mpq_t
          SUBTRAHEND)
     Set DIFFERENCE to MINUEND - SUBTRAHEND.

 - Function: void mpq_mul (mpq_t PRODUCT, mpq_t MULTIPLIER, mpq_t
          MULTIPLICAND)
     Set PRODUCT to MULTIPLIER times MULTIPLICAND.

 - Function: void mpq_mul_2exp (mpq_t ROP, mpq_t OP1, unsigned long int
          OP2)
     Set ROP to OP1 times 2 raised to OP2.

 - Function: void mpq_div (mpq_t QUOTIENT, mpq_t DIVIDEND, mpq_t
          DIVISOR)
     Set QUOTIENT to DIVIDEND/DIVISOR.

 - Function: void mpq_div_2exp (mpq_t ROP, mpq_t OP1, unsigned long int
          OP2)
     Set ROP to OP1 divided by 2 raised to OP2.

 - Function: void mpq_neg (mpq_t NEGATED_OPERAND, mpq_t OPERAND)
     Set NEGATED_OPERAND to -OPERAND.

 - Function: void mpq_abs (mpq_t ROP, mpq_t OP)
     Set ROP to the absolute value of OP.

 - Function: void mpq_inv (mpq_t INVERTED_NUMBER, mpq_t NUMBER)
     Set INVERTED_NUMBER to 1/NUMBER.  If the new denominator is zero,
     this routine will divide by zero.


File: gmp.info,  Node: Comparing Rationals,  Next: Applying Integer Functions,  Prev: Rational Arithmetic,  Up: Rational Number Functions

Comparison Functions
====================

 - Function: int mpq_cmp (mpq_t OP1, mpq_t OP2)
     Compare OP1 and OP2.  Return a positive value if OP1 > OP2, zero
     if OP1 = OP2, and a negative value if OP1 < OP2.

     To determine if two rationals are equal, `mpq_equal' is faster than
     `mpq_cmp'.

 - Macro: int mpq_cmp_ui (mpq_t OP1, unsigned long int NUM2, unsigned
          long int DEN2)
 - Macro: int mpq_cmp_si (mpq_t OP1, long int NUM2, unsigned long int
          DEN2)
     Compare OP1 and NUM2/DEN2.  Return a positive value if OP1 >
     NUM2/DEN2, zero if OP1 = NUM2/DEN2, and a negative value if OP1 <
     NUM2/DEN2.

     NUM2 and DEN2 are allowed to have common factors.

     These functions are implemented as a macros and evaluate their
     arguments multiple times.

 - Macro: int mpq_sgn (mpq_t OP)
     Return +1 if OP > 0, 0 if OP = 0, and -1 if OP < 0.

     This function is actually implemented as a macro.  It evaluates its
     arguments multiple times.

 - Function: int mpq_equal (mpq_t OP1, mpq_t OP2)
     Return non-zero if OP1 and OP2 are equal, zero if they are
     non-equal.  Although `mpq_cmp' can be used for the same purpose,
     this function is much faster.


File: gmp.info,  Node: Applying Integer Functions,  Next: I/O of Rationals,  Prev: Comparing Rationals,  Up: Rational Number Functions

Applying Integer Functions to Rationals
=======================================

   The set of `mpq' functions is quite small.  In particular, there are
few functions for either input or output.  The following functions give
direct access to the numerator and denominator of an `mpq_t'.

   Note that if an assignment to the numerator and/or denominator could
take an `mpq_t' out of the canonical form described at the start of
this chapter (*note Rational Number Functions::) then
`mpq_canonicalize' must be called before any other `mpq' functions are
applied to that `mpq_t'.

 - Macro: mpz_t mpq_numref (mpq_t OP)
 - Macro: mpz_t mpq_denref (mpq_t OP)
     Return a reference to the numerator and denominator of OP,
     respectively.  The `mpz' functions can be used on the result of
     these macros.

 - Function: void mpq_get_num (mpz_t NUMERATOR, mpq_t RATIONAL)
 - Function: void mpq_get_den (mpz_t DENOMINATOR, mpq_t RATIONAL)
 - Function: void mpq_set_num (mpq_t RATIONAL, mpz_t NUMERATOR)
 - Function: void mpq_set_den (mpq_t RATIONAL, mpz_t DENOMINATOR)
     Get or set the numerator or denominator of a rational.  These
     functions are equivalent to calling `mpz_set' with an appropriate
     `mpq_numref' or `mpq_denref'.  Direct use of `mpq_numref' or
     `mpq_denref' is recommended instead of these functions.


File: gmp.info,  Node: I/O of Rationals,  Prev: Applying Integer Functions,  Up: Rational Number Functions

Input and Output Functions
==========================

   When using any of these functions, it's a good idea to include
`stdio.h' before `gmp.h', since that will allow `gmp.h' to define
prototypes for these functions.

   Passing a `NULL' pointer for a STREAM argument to any of these
functions will make them read from `stdin' and write to `stdout',
respectively.

 - Function: size_t mpq_out_str (FILE *STREAM, int BASE, mpq_t OP)
     Output OP on stdio stream STREAM, as a string of digits in base
     BASE.  The base may vary from 2 to 36.  Output is in the form
     `num/den' or if the denominator is 1 then just `num'.

     Return the number of bytes written, or if an error occurred,
     return 0.

 - Function: size_t mpq_inp_str (mpq_t ROP, FILE *STREAM, int BASE)
     Read a string of digits from STREAM and convert them to a rational
     in ROP.  Any initial white-space characters are read and
     discarded.  Return the number of characters read (including white
     space), or 0 if a rational could not be read.

     The input can be a fraction like `17/63' or just an integer like
     `123'.  Reading stops at the first character not in this form, and
     white space is not permitted within the string.  If the input
     might not be in canonical form, then `mpq_canonicalize' must be
     called (*note Rational Number Functions::).

     The BASE can be between 2 and 36, or can be 0 in which case the
     leading characters of the string determine the base, `0x' or `0X'
     for hexadecimal, `0' for octal, or decimal otherwise.  The leading
     characters are examined separately for the numerator and
     denominator of a fraction, so for instance `0x10/11' is 16/11,
     whereas `0x10/0x11' is 16/17.


File: gmp.info,  Node: Floating-point Functions,  Next: Low-level Functions,  Prev: Rational Number Functions,  Up: Top

Floating-point Functions
************************

   GMP floating point numbers are stored in objects of type `mpf_t' and
functions operating on them have an `mpf_' prefix.

   The mantissa of each float has a user-selectable precision, limited
only by available memory.  Each variable has its own precision, and
that can be increased or decreased at any time.

   The exponent of each float is a fixed precision, one machine word on
most systems.  In the current implementation the exponent is a count of
limbs, so for example on a 32-bit system this means a range of roughly
2^-68719476768 to 2^68719476736, or on a 64-bit system this will be
greater.  Note however `mpf_get_str' can only return an exponent which
fits an `mp_exp_t' and currently `mpf_set_str' doesn't accept exponents
bigger than a `long'.

   Each variable keeps a size for the mantissa data actually in use.
This means that if a float is exactly represented in only a few bits
then only those bits will be used in a calculation, even if the
selected precision is high.

   All calculations are performed to the precision of the destination
variable.  Each function is defined to calculate with "infinite
precision" followed by a truncation to the destination precision, but
of course the work done is only what's needed to determine a result
under that definition.

   The precision selected for a variable is a minimum value, GMP may
increase it a little to facilitate efficient calculation.  Currently
this means rounding up to a whole limb, and then sometimes having a
further partial limb, depending on the high limb of the mantissa.  But
applications shouldn't be concerned by such details.

   `mpf' functions and variables have no special notion of infinity or
not-a-number, and applications must take care not to overflow the
exponent or results will be unpredictable.  This might change in a
future release.

   Note that the `mpf' functions are _not_ intended as a smooth
extension to IEEE P754 arithmetic.  In particular results obtained on
one computer often differ from the results on a computer with a
different word size.

* Menu:

* Initializing Floats::
* Assigning Floats::
* Simultaneous Float Init & Assign::
* Converting Floats::
* Float Arithmetic::
* Float Comparison::
* I/O of Floats::
* Miscellaneous Float Functions::


File: gmp.info,  Node: Initializing Floats,  Next: Assigning Floats,  Prev: Floating-point Functions,  Up: Floating-point Functions

Initialization Functions
========================

 - Function: void mpf_set_default_prec (unsigned long int PREC)
     Set the default precision to be *at least* PREC bits.  All
     subsequent calls to `mpf_init' will use this precision, but
     previously initialized variables are unaffected.

 - Function: unsigned long int mpf_get_default_prec (void)
     Return the default default precision actually used.

   An `mpf_t' object must be initialized before storing the first value
in it.  The functions `mpf_init' and `mpf_init2' are used for that
purpose.

 - Function: void mpf_init (mpf_t X)
     Initialize X to 0.  Normally, a variable should be initialized
     once only or at least be cleared, using `mpf_clear', between
     initializations.  The precision of X is undefined unless a default
     precision has already been established by a call to
     `mpf_set_default_prec'.

 - Function: void mpf_init2 (mpf_t X, unsigned long int PREC)
     Initialize X to 0 and set its precision to be *at least* PREC
     bits.  Normally, a variable should be initialized once only or at
     least be cleared, using `mpf_clear', between initializations.

 - Function: void mpf_clear (mpf_t X)
     Free the space occupied by X.  Make sure to call this function for
     all `mpf_t' variables when you are done with them.

   Here is an example on how to initialize floating-point variables:
     {
       mpf_t x, y;
       mpf_init (x);			/* use default precision */
       mpf_init2 (y, 256);		/* precision _at least_ 256 bits */
       ...
       /* Unless the program is about to exit, do ... */
       mpf_clear (x);
       mpf_clear (y);
     }

   The following three functions are useful for changing the precision
during a calculation.  A typical use would be for adjusting the
precision gradually in iterative algorithms like Newton-Raphson, making
the computation precision closely match the actual accurate part of the
numbers.

 - Function: unsigned long int mpf_get_prec (mpf_t OP)
     Return the current precision of OP, in bits.

 - Function: void mpf_set_prec (mpf_t ROP, unsigned long int PREC)
     Set the precision of ROP to be *at least* PREC bits.  The value in
     ROP will be truncated to the new precision.

     This function requires a call to `realloc', and so should not be
     used in a tight loop.

 - Function: void mpf_set_prec_raw (mpf_t ROP, unsigned long int PREC)
     Set the precision of ROP to be *at least* PREC bits, without
     changing the memory allocated.

     PREC must be no more than the allocated precision for ROP, that
     being the precision when ROP was initialized, or in the most recent
     `mpf_set_prec'.

     The value in ROP is unchanged, and in particular if it had a higher
     precision than PREC it will retain that higher precision.  New
     values written to ROP will use the new PREC.

     Before calling `mpf_clear' or the full `mpf_set_prec', another
     `mpf_set_prec_raw' call must be made to restore ROP to its original
     allocated precision.  Failing to do so will have unpredictable
     results.

     `mpf_get_prec' can be used before `mpf_set_prec_raw' to get the
     original allocated precision.  After `mpf_set_prec_raw' it
     reflects the PREC value set.

     `mpf_set_prec_raw' is an efficient way to use an `mpf_t' variable
     at different precisions during a calculation, perhaps to gradually
     increase precision in an iteration, or just to use various
     different precisions for different purposes during a calculation.


File: gmp.info,  Node: Assigning Floats,  Next: Simultaneous Float Init & Assign,  Prev: Initializing Floats,  Up: Floating-point Functions

Assignment Functions
====================

   These functions assign new values to already initialized floats
(*note Initializing Floats::).

 - Function: void mpf_set (mpf_t ROP, mpf_t OP)
 - Function: void mpf_set_ui (mpf_t ROP, unsigned long int OP)
 - Function: void mpf_set_si (mpf_t ROP, signed long int OP)
 - Function: void mpf_set_d (mpf_t ROP, double OP)
 - Function: void mpf_set_z (mpf_t ROP, mpz_t OP)
 - Function: void mpf_set_q (mpf_t ROP, mpq_t OP)
     Set the value of ROP from OP.

 - Function: int mpf_set_str (mpf_t ROP, char *STR, int BASE)
     Set the value of ROP from the string in STR.  The string is of the
     form `M@N' or, if the base is 10 or less, alternatively `MeN'.
     `M' is the mantissa and `N' is the exponent.  The mantissa is
     always in the specified base.  The exponent is either in the
     specified base or, if BASE is negative, in decimal.  The decimal
     point expected is taken from the current locale, on systems
     providing `localeconv'.

     The argument BASE may be in the ranges 2 to 36, or -36 to -2.
     Negative values are used to specify that the exponent is in
     decimal.

     Unlike the corresponding `mpz' function, the base will not be
     determined from the leading characters of the string if BASE is 0.
     This is so that numbers like `0.23' are not interpreted as octal.

     White space is allowed in the string, and is simply ignored.
     [This is not really true; white-space is ignored in the beginning
     of the string and within the mantissa, but not in other places,
     such as after a minus sign or in the exponent.  We are considering
     changing the definition of this function, making it fail when
     there is any white-space in the input, since that makes a lot of
     sense.  Please tell us your opinion about this change.  Do you
     really want it to accept "3 14" as meaning 314 as it does now?]

     This function returns 0 if the entire string is a valid number in
     base BASE.  Otherwise it returns -1.

 - Function: void mpf_swap (mpf_t ROP1, mpf_t ROP2)
     Swap ROP1 and ROP2 efficiently.  Both the values and the
     precisions of the two variables are swapped.


File: gmp.info,  Node: Simultaneous Float Init & Assign,  Next: Converting Floats,  Prev: Assigning Floats,  Up: Floating-point Functions

Combined Initialization and Assignment Functions
================================================

   For convenience, GMP provides a parallel series of
initialize-and-set functions which initialize the output and then store
the value there.  These functions' names have the form `mpf_init_set...'

   Once the float has been initialized by any of the `mpf_init_set...'
functions, it can be used as the source or destination operand for the
ordinary float functions.  Don't use an initialize-and-set function on
a variable already initialized!

 - Function: void mpf_init_set (mpf_t ROP, mpf_t OP)
 - Function: void mpf_init_set_ui (mpf_t ROP, unsigned long int OP)
 - Function: void mpf_init_set_si (mpf_t ROP, signed long int OP)
 - Function: void mpf_init_set_d (mpf_t ROP, double OP)
     Initialize ROP and set its value from OP.

     The precision of ROP will be taken from the active default
     precision, as set by `mpf_set_default_prec'.

 - Function: int mpf_init_set_str (mpf_t ROP, char *STR, int BASE)
     Initialize ROP and set its value from the string in STR.  See
     `mpf_set_str' above for details on the assignment operation.

     Note that ROP is initialized even if an error occurs.  (I.e., you
     have to call `mpf_clear' for it.)

     The precision of ROP will be taken from the active default
     precision, as set by `mpf_set_default_prec'.


File: gmp.info,  Node: Converting Floats,  Next: Float Arithmetic,  Prev: Simultaneous Float Init & Assign,  Up: Floating-point Functions

Conversion Functions
====================

 - Function: double mpf_get_d (mpf_t OP)
     Convert OP to a `double'.

 - Function: double mpf_get_d_2exp (signed long int EXP, mpf_t OP)
     Find D and EXP such that D times 2 raised to EXP, with
     0.5<=abs(D)<1, is a good approximation to OP.  This is similar to
     the standard C function `frexp'.

 - Function: long mpf_get_si (mpf_t OP)
 - Function: unsigned long mpf_get_ui (mpf_t OP)
     Convert OP to a `long' or `unsigned long', truncating any fraction
     part.  If OP is too big for the return type, the result is
     undefined.

     See also `mpf_fits_slong_p' and `mpf_fits_ulong_p' (*note
     Miscellaneous Float Functions::).

 - Function: char * mpf_get_str (char *STR, mp_exp_t *EXPPTR, int BASE,
          size_t N_DIGITS, mpf_t OP)
     Convert OP to a string of digits in base BASE.  BASE can be 2 to
     36.  Up to N_DIGITS digits will be generated.  Trailing zeros are
     not returned.  No more digits than can be accurately represented
     by OP are ever generated.  If N_DIGITS is 0 then that accurate
     maximum number of digits are generated.

     If STR is `NULL', the result string is allocated using the current
     allocation function (*note Custom Allocation::).  The block will be
     `strlen(str)+1' bytes, that being exactly enough for the string and
     null-terminator.

     If STR is not `NULL', it should point to a block of N_DIGITS + 2
     bytes, that being enough for the mantissa, a possible minus sign,
     and a null-terminator.  When N_DIGITS is 0 to get all significant
     digits, an application won't be able to know the space required,
     and STR should be `NULL' in that case.

     The generated string is a fraction, with an implicit radix point
     immediately to the left of the first digit.  The applicable
     exponent is written through the EXPPTR pointer.  For example, the
     number 3.1416 would be returned as string "31416" and exponent 1.

     When OP is zero, an empty string is produced and the exponent
     returned is 0.

     A pointer to the result string is returned, being either the
     allocated block or the given STR.


File: gmp.info,  Node: Float Arithmetic,  Next: Float Comparison,  Prev: Converting Floats,  Up: Floating-point Functions

Arithmetic Functions
====================

 - Function: void mpf_add (mpf_t ROP, mpf_t OP1, mpf_t OP2)
 - Function: void mpf_add_ui (mpf_t ROP, mpf_t OP1, unsigned long int
          OP2)
     Set ROP to OP1 + OP2.

 - Function: void mpf_sub (mpf_t ROP, mpf_t OP1, mpf_t OP2)
 - Function: void mpf_ui_sub (mpf_t ROP, unsigned long int OP1, mpf_t
          OP2)
 - Function: void mpf_sub_ui (mpf_t ROP, mpf_t OP1, unsigned long int
          OP2)
     Set ROP to OP1 - OP2.

 - Function: void mpf_mul (mpf_t ROP, mpf_t OP1, mpf_t OP2)
 - Function: void mpf_mul_ui (mpf_t ROP, mpf_t OP1, unsigned long int
          OP2)
     Set ROP to OP1 times OP2.

   Division is undefined if the divisor is zero, and passing a zero
divisor to the divide functions will make these functions intentionally
divide by zero.  This lets the user handle arithmetic exceptions in
these functions in the same manner as other arithmetic exceptions.

 - Function: void mpf_div (mpf_t ROP, mpf_t OP1, mpf_t OP2)
 - Function: void mpf_ui_div (mpf_t ROP, unsigned long int OP1, mpf_t
          OP2)
 - Function: void mpf_div_ui (mpf_t ROP, mpf_t OP1, unsigned long int
          OP2)
     Set ROP to OP1/OP2.

 - Function: void mpf_sqrt (mpf_t ROP, mpf_t OP)
 - Function: void mpf_sqrt_ui (mpf_t ROP, unsigned long int OP)
     Set ROP to the square root of OP.

 - Function: void mpf_pow_ui (mpf_t ROP, mpf_t OP1, unsigned long int
          OP2)
     Set ROP to OP1 raised to the power OP2.

 - Function: void mpf_neg (mpf_t ROP, mpf_t OP)
     Set ROP to -OP.

 - Function: void mpf_abs (mpf_t ROP, mpf_t OP)
     Set ROP to the absolute value of OP.

 - Function: void mpf_mul_2exp (mpf_t ROP, mpf_t OP1, unsigned long int
          OP2)
     Set ROP to OP1 times 2 raised to OP2.

 - Function: void mpf_div_2exp (mpf_t ROP, mpf_t OP1, unsigned long int
          OP2)
     Set ROP to OP1 divided by 2 raised to OP2.


File: gmp.info,  Node: Float Comparison,  Next: I/O of Floats,  Prev: Float Arithmetic,  Up: Floating-point Functions

Comparison Functions
====================

 - Function: int mpf_cmp (mpf_t OP1, mpf_t OP2)
 - Function: int mpf_cmp_d (mpf_t OP1, double OP2)
 - Function: int mpf_cmp_ui (mpf_t OP1, unsigned long int OP2)
 - Function: int mpf_cmp_si (mpf_t OP1, signed long int OP2)
     Compare OP1 and OP2.  Return a positive value if OP1 > OP2, zero
     if OP1 = OP2, and a negative value if OP1 < OP2.

 - Function: int mpf_eq (mpf_t OP1, mpf_t OP2, unsigned long int op3)
     Return non-zero if the first OP3 bits of OP1 and OP2 are equal,
     zero otherwise.  I.e., test of OP1 and OP2 are approximately equal.

     Caution: Currently only whole limbs are compared, and only in an
     exact fashion.  In the future values like 1000 and 0111 may be
     considered the same to 3 bits (on the basis that their difference
     is that small).

 - Function: void mpf_reldiff (mpf_t ROP, mpf_t OP1, mpf_t OP2)
     Compute the relative difference between OP1 and OP2 and store the
     result in ROP.  This is abs(OP1-OP2)/OP1.

 - Macro: int mpf_sgn (mpf_t OP)
     Return +1 if OP > 0, 0 if OP = 0, and -1 if OP < 0.

     This function is actually implemented as a macro.  It evaluates
     its arguments multiple times.


File: gmp.info,  Node: I/O of Floats,  Next: Miscellaneous Float Functions,  Prev: Float Comparison,  Up: Floating-point Functions

Input and Output Functions
==========================

   Functions that perform input from a stdio stream, and functions that
output to a stdio stream.  Passing a `NULL' pointer for a STREAM
argument to any of these functions will make them read from `stdin' and
write to `stdout', respectively.

   When using any of these functions, it is a good idea to include
`stdio.h' before `gmp.h', since that will allow `gmp.h' to define
prototypes for these functions.

 - Function: size_t mpf_out_str (FILE *STREAM, int BASE, size_t
          N_DIGITS, mpf_t OP)
     Print OP to STREAM, as a string of digits.  Return the number of
     bytes written, or if an error occurred, return 0.

     The mantissa is prefixed with an `0.' and is in the given BASE,
     which may vary from 2 to 36.  An exponent then printed, separated
     by an `e', or if BASE is greater than 10 then by an `@'.  The
     exponent is always in decimal.  The decimal point follows the
     current locale, on systems providing `localeconv'.

     Up to N_DIGITS will be printed from the mantissa, except that no
     more digits than are accurately representable by OP will be
     printed.  N_DIGITS can be 0 to select that accurate maximum.

 - Function: size_t mpf_inp_str (mpf_t ROP, FILE *STREAM, int BASE)
     Read a string in base BASE from STREAM, and put the read float in
     ROP.  The string is of the form `M@N' or, if the base is 10 or
     less, alternatively `MeN'.  `M' is the mantissa and `N' is the
     exponent.  The mantissa is always in the specified base.  The
     exponent is either in the specified base or, if BASE is negative,
     in decimal.  The decimal point expected is taken from the current
     locale, on systems providing `localeconv'.

     The argument BASE may be in the ranges 2 to 36, or -36 to -2.
     Negative values are used to specify that the exponent is in
     decimal.

     Unlike the corresponding `mpz' function, the base will not be
     determined from the leading characters of the string if BASE is 0.
     This is so that numbers like `0.23' are not interpreted as octal.

     Return the number of bytes read, or if an error occurred, return 0.


File: gmp.info,  Node: Miscellaneous Float Functions,  Prev: I/O of Floats,  Up: Floating-point Functions

Miscellaneous Functions
=======================

 - Function: void mpf_ceil (mpf_t ROP, mpf_t OP)
 - Function: void mpf_floor (mpf_t ROP, mpf_t OP)
 - Function: void mpf_trunc (mpf_t ROP, mpf_t OP)
     Set ROP to OP rounded to an integer.  `mpf_ceil' rounds to the
     next higher integer, `mpf_floor' to the next lower, and `mpf_trunc'
     to the integer towards zero.

 - Function: int mpf_integer_p (mpf_t OP)
     Return non-zero if OP is an integer.

 - Function: int mpf_fits_ulong_p (mpf_t OP)
 - Function: int mpf_fits_slong_p (mpf_t OP)
 - Function: int mpf_fits_uint_p (mpf_t OP)
 - Function: int mpf_fits_sint_p (mpf_t OP)
 - Function: int mpf_fits_ushort_p (mpf_t OP)
 - Function: int mpf_fits_sshort_p (mpf_t OP)
     Return non-zero if OP would fit in the respective C data type, when
     truncated to an integer.

 - Function: void mpf_urandomb (mpf_t ROP, gmp_randstate_t STATE,
          unsigned long int NBITS)
     Generate a uniformly distributed random float in ROP, such that 0
     <= ROP < 1, with NBITS significant bits in the mantissa.

     The variable STATE must be initialized by calling one of the
     `gmp_randinit' functions (*Note Random State Initialization::)
     before invoking this function.

 - Function: void mpf_random2 (mpf_t ROP, mp_size_t MAX_SIZE, mp_exp_t
          EXP)
     Generate a random float of at most MAX_SIZE limbs, with long
     strings of zeros and ones in the binary representation.  The
     exponent of the number is in the interval -EXP to EXP.  This
     function is useful for testing functions and algorithms, since
     this kind of random numbers have proven to be more likely to
     trigger corner-case bugs.  Negative random numbers are generated
     when MAX_SIZE is negative.

