boxcox1p

Compute a one-parameter Box-Cox transformation of 1+x.

A one-parameter Box-Cox transformation is defined as

y Superscript lamda Baseline equals StartLayout Enlarged left-brace 1st Row 1st Column StartFraction left-parenthesis y plus 1 right-parenthesis Superscript lamda Baseline minus 1 Over lamda EndFraction 2nd Column if lamda not-equals 0 2nd Row 1st Column log left-parenthesis y plus 1 right-parenthesis 2nd Column if lamda equals 0 EndLayout

Usage

var boxcox1p = require( '@stdlib/math/base/special/boxcox1p' );

boxcox1p( x, lambda )

Computes a one-parameter Box-Cox transformation of 1+x.

var v = boxcox1p( 1.0, 2.5 );
// returns ~1.8627

v = boxcox1p( 4.0, 2.5 );
// returns ~21.9607

v = boxcox1p( 10.0, 2.5 );
// returns ~160.1246

v = boxcox1p( 2.0, 0.0 );
// returns ~1.0986

v = boxcox1p( -1.0, 2.5 );
// returns -0.4

v = boxcox1p( 0.0, -1.0 );
// returns 0.0

v = boxcox1p( -1.0, -1.0 );
// returns -Infinity

Examples

var incrspace = require( '@stdlib/array/base/incrspace' );
var boxcox1p = require( '@stdlib/math/base/special/boxcox1p' );

var x = incrspace( -1.0, 10.0, 1.0 );
var l = incrspace( -0.5, 5.0, 0.5 );

var b;
var i;
var j;
for ( i = 0; i < x.length; i++ ) {
    for ( j = 0; j < l.length; j++ ) {
        b = boxcox1p( x[ i ], l[ j ] );
        console.log( 'boxcox1p(%d, %d) = %d', x[ i ], l[ j ], b );
    }
}

References

  • Box, G. E. P., and D. R. Cox. 1964. "An Analysis of Transformations." Journal of the Royal Statistical Society. Series B (Methodological) 26 (2). [Royal Statistical Society, Wiley]: 211–52. http://www.jstor.org/stable/2984418.
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