Compute `x * ln(y)` so that the result is `0` if `x = 0`.
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> Compute x * ln(y) so that the result is 0 if x = 0.
``bash`
npm install @stdlib/math-base-special-xlogy
`javascript`
var xlogy = require( '@stdlib/math-base-special-xlogy' );
#### xlogy( x, y )
Computes x * ln(y) so that the result is 0 if x = 0.
`javascript
var out = xlogy( 3.0, 2.0 );
// returns ~2.079
out = xlogy( 1.5, 5.9 );
// returns ~2.662
out = xlogy( 0.9, 1.0 );
// returns 0.0
out = xlogy( 0.0, -2.0 );
// returns 0.0
out = xlogy( 1.5, NaN );
// returns NaN
out = xlogy( 0.0, NaN );
// returns NaN
out = xlogy( NaN, 2.3 );
// returns NaN
`
`javascript
var randu = require( '@stdlib/random-base-randu' );
var xlogy = require( '@stdlib/math-base-special-xlogy' );
var x;
var y;
var i;
for ( i = 0; i < 100; i++ ) {
x = randu();
if ( x < 0.5 ) {
x = 0.0;
}
y = ( randu() * 20.0 ) - 5.0;
console.log( 'xlogy(%d, %d) = %d', x, y, xlogy( x, y ) );
}
`
*
`c`
#include "stdlib/math/base/special/xlogy.h"
#### stdlib_base_xlogy( x, y )
Computes x * ln(y) so that the result is 0 if x = 0.
`c`
double v = stdlib_base_xlogy( 3.0, 2.0 );
// returns ~2.079
The function accepts the following arguments:
- x: [in] double input value.[in] double
- y: input value.
`c`
double stdlib_base_xlogy( const double x, const double y );
`c
#include "stdlib/math/base/special/xlogy.h"
#include
#include
int main( void ) {
double out;
double x;
double y;
int i;
for ( i = 0; i < 100; i++ ) {
x = ( (double)rand() / (double)RAND_MAX ) * 100.0;
y = ( (double)rand() / (double)RAND_MAX ) * 5.0;
out = stdlib_base_xlogy( x, y );
printf( "xlogy(%lf, %lf) = %lf\n", x, y, out );
}
}
`
*
- [@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/xlog1py][@stdlib/math/base/special/xlog1py]: compute x * ln(y+1) so that the result is 0 if x = 0.
*
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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[@stdlib/math/base/special/ln]: https://www.npmjs.com/package/@stdlib/math-base-special-ln
[@stdlib/math/base/special/xlog1py]: https://www.npmjs.com/package/@stdlib/math-base-special-xlog1py