DZone Snippets: Toxi's Code Snippets

Customizable sigmoid function

toxi (karsten schmidt) — Mon, 18 Sep 2006 17:23:30 GMT



/**

 * Calculates S-curve for point x in the interval 0 .. normV

 * 

 * @param x input coordinate

 * @param normV scale value which corresponds to 1.0 if x is normalized

 * @param sharpness adjusts steepness of curve (value of 1 equals undistorted sigmoid)

 *

 * @return sigmoid for point X

 */

public float sigmoid(float x, float normV, float sharpness) {

  x=(x/normV*2-1)*5*sharpness;

  return 1.0f / (1.0f + (float)Math.exp(-x));

}



public double sigmoid(double x, double normV, double sharpness) {

  x=(x/normV*2-1)*5*sharpness;

  return 1.0 / (1.0 + Math.exp(-x));

}

baseX converter

toxi (karsten schmidt) — Tue, 19 Jul 2005 19:55:29 GMT

you can use this function to convert an integer into any number system upto base36 (e.g. for TinyURL generation coupled with a global ID counter)

function int2baseX($val,$base=16) {

  if (0==$val) return 0;

  $symbols='0123456789abcdefgihjklmnopqrstuvwxyz';

  $result='';

  $exp=$oldpow=1;

  while($val>0 && $exp<10) {

    $pow=pow($base,$exp++);

    $mod=($val % $pow);

    $result=substr($symbols,$mod/$oldpow,1).$result;

    $val-=$mod;

    $oldpow=$pow;

  }

  return $result;

}

create pre-styled/populated DOM elements

toxi (karsten schmidt) — Thu, 07 Apr 2005 23:18:59 GMT



/*

 * create a new DOM element with (optionally) specified className, CSS and text/html content

 * if text contains any markup, it's used as innerHTML value - else a child text node is attached

 * if there's also a parent node given, the new element will be appended as child node

 */

function createStyledElement(tag, parent, cls, css, txt) {

    var el = document.createElement(tag);

    if(cls) el.className = cls;

    if(css) for(var s in css) el.style[s]=css[s];

    if(txt) {

        if (txt.indexOf('<')!=-1) el.innerHTML=txt;

        else el.appendChild(document.createTextNode(txt));

    }

    if(parent) parent.appendChild(el);

    return el;

}



// usage example...

// 1st define some style params

var style1={

    background: '#def',

    color: '#f00',

    padding: '0.5em',

    border: '1px black dotted'

};



createStyledElement(

  'div',

  document.getElementsByTagName('body').item(0),

  null,

  style1,

  'hello world!'

);