0.2.2 • Published 23 days ago
@stdlib/math-base-special-log v0.2.2
Logarithm
Compute the base
b
logarithm.
Installation
npm install @stdlib/math-base-special-log
Usage
var log = require( '@stdlib/math-base-special-log' );
log( x, b )
Computes the base b
logarithm of x
.
var v = log( 100.0, 10.0 );
// returns 2.0
v = log( 16.0, 2.0 );
// returns 4.0
v = log( 5.0, 1.0 );
// returns Infinity
For negative x
or b
, the logarithm is not defined.
var v = log( -4.0, 1.0 );
// returns NaN
v = log( 2.0, -4.0 );
// returns NaN
Examples
var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var log = require( '@stdlib/math-base-special-log' );
var b;
var x;
var i;
for ( i = 0; i < 100; i++ ) {
x = round( randu() * 100.0 );
b = round( randu() * 5.0 );
console.log( 'log( %d, %d ) = %d', x, b, log( x, b ) );
}
C APIs
Usage
#include "stdlib/math/base/special/log.h"
stdlib_base_log( x, b )
Computes the base b
logarithm of x
.
double v = stdlib_base_log( 100.0, 10.0 );
// returns 2.0
The function accepts the following arguments:
- x:
[in] double
input value. - b:
[in] double
input value.
double stdlib_base_log( const double x, const double b );
Examples
#include "stdlib/math/base/special/log.h"
#include <stdlib.h>
#include <stdio.h>
int main( void ) {
double out;
double x;
double b;
int i;
for ( i = 0; i < 100; i++ ) {
x = ( (double)rand() / (double)RAND_MAX ) * 100.0;
b = ( (double)rand() / (double)RAND_MAX ) * 5.0;
out = stdlib_base_log( x, b );
printf( "log(%lf, %lf) = %lf\n", x, b, out );
}
}
See Also
@stdlib/math-base/special/exp
: natural exponential function.@stdlib/math-base/special/ln
: evaluate the natural logarithm of a double-precision floating-point number.@stdlib/math-base/special/log10
: common logarithm (base ten).@stdlib/math-base/special/log1p
: evaluate the natural logarithm of 1+x.@stdlib/math-base/special/log2
: binary logarithm (base 2).
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.
Community
License
See LICENSE.
Copyright
Copyright © 2016-2024. The Stdlib Authors.