Compute an integer binary logarithm (base two).
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> Compute an integer [binary logarithm][binary-logarithm].
``bash`
npm install @stdlib/math-base-special-fast-uint32-log2
`javascript`
var log2Uint32 = require( '@stdlib/math-base-special-fast-uint32-log2' );
#### log2Uint32( x )
Returns an approximate [binary logarithm][binary-logarithm] of an unsigned 32-bit integer x.
`javascript
var v = log2Uint32( 4 >>> 0 );
// returns 2
v = log2Uint32( 8 >>> 0 );
// returns 3
v = log2Uint32( 9 >>> 0 );
// returns 3
`
- This implementation provides a performance boost when an application requires only approximate computations for integer arguments.
- For applications requiring high-precision, this implementation is never suitable.
`javascript
var log2Uint32 = require( '@stdlib/math-base-special-fast-uint32-log2' );
var v;
var i;
for ( i = 1; i < 101; i++ ) {
v = log2Uint32( i >>> 0 );
console.log( 'log2(%d) ≈ %d', i, v );
}
`
*
`c`
#include "stdlib/math/base/special/fast/uint32_log2.h"
#### stdlib_base_fast_uint32_log2( x )
Returns an approximate [binary logarithm][binary-logarithm] of an unsigned 32-bit integer x.
`c
#include
uint32_t out = stdlib_base_fast_uint32_log2( 4 );
// returns 2
out = stdlib_base_fast_uint32_log2( 9 );
// returns 3
`
The function accepts the following arguments:
- x: [in] uint32_t input value.
`c`
uint32_t stdlib_base_fast_uint32_log2( const uint32_t x );
`c
#include "stdlib/math/base/special/fast/uint32_log2.h"
#include
#include
int main( void ) {
const uint32_t x[] = { 5, 7, 10, 22, 98 };
uint32_t y;
int i;
for ( i = 0; i < 5; i++ ) {
y = stdlib_base_fast_uint32_log2( x[ i ] );
printf( "uint32_log2(%u) = %u\n", x[ i ], y );
}
}
`
*
- [@stdlib/math-base/special/log2][@stdlib/math/base/special/log2]: binary logarithm (base 2).
*
This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].
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---
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