exponent

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

Usage

var exponent = require( '@stdlib/number/float64/base/exponent' );

exponent( x )

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

var exp = exponent( 3.14e307 ); // => 2**1021 ~ 1e307
// returns 1021

exp = exponent( 3.14e-307 ); // => 2**-1019 ~ 1e-307
// returns -1019

exp = exponent( -3.14 );
// returns 1

exp = exponent( 0.0 );
// returns -1023

exp = exponent( NaN );
// returns 1024

Examples

var randu = require( '@stdlib/random/base/uniform' );
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
var pow = require( '@stdlib/math/base/special/pow' );
var exponent = require( '@stdlib/number/float64/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( 0.0, 10.0 );
    exp = discreteUniform( -323, 323 );
    x = frac * pow( 10.0, exp );
    e = exponent( x );
    console.log( 'x: %d. unbiased exponent: %d.', x, e );
}

C APIs

Usage

#include "stdlib/number/float64/base/exponent.h"

stdlib_base_float64_exponent( x )

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

#include <stdint.h>

int32_t out = stdlib_base_float64_exponent( 3.14 );

The function accepts the following arguments:

x: [in] double input value.

int32_t stdlib_base_float64_exponent( const double x );

Examples

#include "stdlib/number/float64/base/exponent.h"
#include <stdint.h>
#include <stdio.h>
#include <inttypes.h>

int main( void ) {
    double x[] = { 4.0, 0.0, -0.0, 1.0, -1.0, 3.14, -3.14, 1.0e308, -1.0e308, 1.0/0.0, -1.0/0.0, 0.0/0.0 };

    int32_t out;
    int i;
    for ( i = 0; i < 12; i++ ) {
        out = stdlib_base_float64_exponent( x[ i ] );
        printf( "%lf => out: %" PRId32 "\n", x[ i ], out );
    }
}