@stdlib/number-float32-base-exponent NPM

exponentf

Return an integer corresponding to the unbiased exponent of a single-precision floating-point number.

Installation

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

Usage

var exponentf = require( '@stdlib/number-float32-base-exponent' );

exponentf( x )

Returns an integer corresponding to the unbiased exponent of a single-precision floating-point number.

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

var exp = exponentf( toFloat32( 3.14e34 ) ); // => 2^114 ~ 2.08e34
// returns 114

exp = exponentf( toFloat32( 3.14e-34 ) ); //  => 2^-112 ~ 1.93e-34
// returns -112

exp = exponentf( toFloat32( -3.14 ) );
// returns 1

exp = exponentf( 0.0 );
// returns -127

exp = exponentf( NaN );
// returns 128

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 exponentf = require( '@stdlib/number-float32-base-exponent' );

var frac;
var exp;
var x;
var e;
var i;

// Generate random numbers and extract their exponents...
for ( i = 0; i < 100; i++ ) {
    frac = randu() * 10.0;
    exp = round( randu()*44.0 ) - 22;
    x = frac * pow( 10.0, exp );
    x = toFloat32( x );
    e = exponentf( x );
    console.log( 'x: %d. unbiased exponent: %d.', x, e );
}

C APIs

Usage

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

stdlib_base_float32_exponent( x )

Returns an integer corresponding to the unbiased exponent of a single-precision floating-point number.

#include <stdint.h>

int32_t out = stdlib_base_float32_exponent( 3.14f );

The function accepts the following arguments:

x: [in] float input value.

int32_t stdlib_base_float32_exponent( const float x );

Examples

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

int main( void ) {
    float x[] = { 4.0f, 0.0f, -0.0f, 1.0f, -1.0f, 3.14f, -3.14f, 1.0e38f, -1.0e38f, 1.0f/0.0f, -1.0f/0.0f, 0.0f/0.0f };

    int32_t out;
    int i;
    for ( i = 0; i < 12; i++ ) {
        out = stdlib_base_float32_exponent( x[ i ] );
        printf( "%f => out: %" PRId32 "\n", x[ i ], out );
    }
}

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.