exponentf

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

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 );
    }
}