@stdlib/number-float32-base-normalize NPM

normalizef

Return a normal number y and exponent exp satisfying x = y * 2^exp.

Installation

npm install @stdlib/number-float32-base-normalize

Usage

var normalizef = require( '@stdlib/number-float32-base-normalize' );

normalizef( x )

Returns a normal number y and exponent exp satisfying x = y * 2^exp.

var toFloat32 = require( '@stdlib/number-float64-base-to-float32' );

var out = normalizef( toFloat32( 1.401e-45 ) );
// returns [ 1.1754943508222875e-38, -23 ]

By default, the function returns y and exp as a two-element array.

var toFloat32 = require( '@stdlib/number-float64-base-to-float32' );
var pow = require( '@stdlib/math-base-special-pow' );

var out = normalizef( toFloat32( 1.401e-45 ) );
// returns [ 1.1754943508222875e-38, -23 ]

var y = out[ 0 ];
var exp = out[ 1 ];

var bool = ( y*pow(2, exp) === toFloat32(1.401e-45) );
// returns true

The function expects a finite, non-zero single-precision floating-point number x. If x == 0,

var out = normalizef( 0.0 );
// returns [ 0.0, 0 ];

If x is either positive or negative infinity or NaN,

var PINF = require( '@stdlib/constants-float32-pinf' );
var NINF = require( '@stdlib/constants-float32-ninf' );

var out = normalizef( PINF );
// returns [ Infinity, 0 ]

out = normalizef( NINF );
// returns [ -Infinity, 0 ]

out = normalizef( NaN );
// returns [ NaN, 0 ]

normalizef( x, out, stride, offset )

Returns a normal number y and exponent exp satisfying x = y * 2^exp and assigns results to a provided output array.

var toFloat32 = require( '@stdlib/number-float64-base-to-float32' );
var Float32Array = require( '@stdlib/array-float32' );

var out = new Float32Array( 2 );

var v = normalizef.assign( toFloat32( 1.401e-45 ), out, 1, 0 );
// returns <Float32Array>[ 1.1754943508222875e-38, -23 ]

var bool = ( v === out );
// returns true

Notes

While the function accepts higher precision floating-point numbers, beware that providing such numbers can be a source of subtle bugs as the relation x = y * 2^exp may not hold.

Examples

var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var pow = require( '@stdlib/math-base-special-pow' );
var toFloat32 = require( '@stdlib/number-float64-base-to-float32' );
var normalizef = require( '@stdlib/number-float32-base-normalize' );

var frac;
var exp;
var x;
var v;
var i;

// Generate denormalized single-precision floating-point numbers and then normalize them...
for ( i = 0; i < 100; i++ ) {
    frac = randu() * 10.0;
    exp = 38 + round( randu()*6.0 );
    x = frac * pow( 10.0, -exp );
    x = toFloat32( x );
    v = normalizef( x );
    console.log( '%d = %d * 2^%d = %d', x, v[0], v[1], v[0]*pow(2.0, v[1]) );
}

C APIs

Usage

#include "stdlib/number/float32/base/normalize.h"

stdlib_base_float32_normalize( x, y, exp )

Returns a normal number y and exponent exp satisfying x = y * 2^exp.

#include <stdint.h>

float y;
int32_t exp;
stdlib_base_float32_normalize( 3.14, &y, &exp );

The function accepts the following arguments:

x: [in] float input value.
y: [out] float* destination for normal number.
exp: [out] int32_t* destination for exponent.

void stdlib_base_float32_normalize( const float x, float *y, int32_t *exp );

Examples

#include "stdlib/number/float32/base/normalize.h"
#include <stdint.h>
#include <stdio.h>

int main( void ) {
    float x[] = { 4.0f, 0.0f, -0.0f, 1.0f, -1.0f, 3.14f, -3.14f, 1.0e-38f, -1.0e-38f, 1.0f/0.0f, -1.0f/0.0f, 0.0f/0.0f };

    int32_t exp;
    float y;
    int i;
    for ( i = 0; i < 12; i++ ) {
        stdlib_base_float32_normalize( x[ i ], &y, &exp );
        printf( "%f => y: %f, exp: %" PRId32 "\n", x[ i ], y, exp );
    }
}

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.