code: @Override
  	public double transform(double value) {
  		double sqrtValue = Double.NEGATIVE_INFINITY;
  		if(value >= 0)
  			sqrtValue = Math.sqrt(value);
  
  		return sqrtValue;
  	}
docs: Return sqrt(value).
  If value is negative, return the color corresponding to negative infinity.
  
  @param value Value to be mapped
  @return sqrt(value), or NEGATIVE_INFINITY
  @see org.biojava.nbio.structure.gui.util.color.ContinuousColorMapper#getColor(double)