acisternino / nelua-mpfr

Nelua bindings to GNU MPFR

nelua-mpfr

Nelua bindings for the GNU MPFR library, version 4.1.

The MPFR library is a C library for multiple-precision floating-point computations with correct rounding.

The MPFR documentation is available here.

Prerequisites

• The GNU MPFR library must be installed in the system or otherwise available to the C compiler.
• GNU MPFR requires, as a hard dependency, the GNU GMP library.

Usage

Drop the mpfr.nelua file in your project and use it with a require 'mpfr'.

In restricted environments where stdio.h is not available you can define the NELUA_MPFR_NO_STDIO symbol in Nelua's preprocessor to remove all IO functions that require the FILE type to be available:

## NELUA_MPFR_NO_STDIO = 1
require `mpfr`

Example

The main type used by GNU MPFR is the mpfr_t record.

Thanks to the automatic referencing performed by the nelua compiler, variables defined as mpfr_t can be passed to most of the functions without the & operator.

However, some functions, namely those using varargs, are defined in such a way that require the reference operator. For an example look at the mpfr_printf call in the following program.

require 'mpfr'

local s: mpfr_t

-- Init 's' with 100 bits of precision and set its value
mpfr_init2(s, 100)
mpfr_set_str(s, '1.3337612', 10, MPFR_RNDN)

-- Multiply by 42 and print the result to stdout
mpfr_mul_ui(s, s, 42, MPFR_RNDN)
mpfr_printf("1.3337612 * 42 is: %.30Rf\n", &s)

-- Clean-up
mpfr_clear(s)
mpfr_free_cache()

A more comprehensive example is available in the mpfr-test.nelua file.

Please refer to the MPFR documentation for more datails.