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log1p
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Evaluate the [natural logarithm][@stdlib/math/base/special/ln] of
1+x.
bash
npm install @stdlib/math-base-special-log1p
javascript
var log1p = require( '@stdlib/math-base-special-log1p' );
#### log1p( x )
Evaluates the [natural logarithm][@stdlib/math/base/special/ln] of 1+x.
javascript
var v = log1p( 4.0 );
// returns ~1.609
v = log1p( -1.0 );
// returns -Infinity
v = log1p( Infinity );
// returns Infinity
v = log1p( 0.0 );
// returns 0.0
v = log1p( -0.0 );
// returns -0.0
v = log1p( NaN );
// returns NaN
For x < -1, the function returns NaN, as the [natural logarithm][@stdlib/math/base/special/ln] is not defined for negative numbers.
javascript
var v = log1p( -2.0 );
// returns NaN
javascript
var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var log1p = require( '@stdlib/math-base-special-log1p' );
var x;
var i;
for ( i = 0; i < 100; i++ ) {
x = round( randu() * 100.0 );
console.log( log1p( x ) );
}
c
#include "stdlib/math/base/special/log1p.h"
#### stdlib_base_log1p( x )
Evaluates the [natural logarithm][@stdlib/math/base/special/ln] of 1+x.
c
double out = stdlib_base_log1p( 4.0 );
// returns ~1.609
out = stdlib_base_log1p( -1.0 );
// returns -Infinity
The function accepts the following arguments:
- x: [in] double input value.
c
double stdlib_base_log1p( const double x );
c
#include "stdlib/math/base/special/log1p.h"
#include <stdlib.h>
#include <stdio.h>
int main( void ) {
double x;
double v;
int i;
for ( i = 0; i < 100; i++ ) {
x = ( (double)rand() / (double)RAND_MAX ) * 100.0;
v = stdlib_base_log1p( x );
printf( "log1p(%lf) = %lf\n", x, v );
}
}
@stdlib/math-base/special/ln][@stdlib/math/base/special/ln]: evaluate the natural logarithm of a double-precision floating-point number.
- [@stdlib/math-base/special/log][@stdlib/math/base/special/log]: base b logarithm.
