src/jquery.nstSlider.js
function (value) {
            var $this = this,
                value_to_pixel_mapping_func = $this.data('value_to_pixel_mapping');

            // try using non-linear mapping if it's there...
            if (typeof value_to_pixel_mapping_func !== 'undefined') {
                return value_to_pixel_mapping_func(value); 
            }

            // ... use linear mapping otherwise
            var w = _methods.getSliderWidthPx.call($this) - $this.data('left_grip_width');
            return _methods.rangemap_0_to_n.call($this, value, w);
        }
function (value) {
            var $this = this,
                value_to_pixel_mapping_func = $this.data('value_to_pixel_mapping');

            // try using non-linear mapping if it's there...
            if (typeof value_to_pixel_mapping_func !== 'undefined') {
                return value_to_pixel_mapping_func(value); 
            }

            // ... use linear mapping otherwise
            var w = _methods.getSliderWidthPx.call($this) - $this.data('left_grip_width');
            return _methods.rangemap_0_to_n.call($this, value, w);
        }
/*
Utility function. Given a value within the range of the slider,
converts the value in pixels. If a value_to_pixel_mapping function
is defined it will be used, otherwise a linear mapping is used for
the conversion.