Proposal for an alternative method to rounding numbers

[veillette]

For numerical readout and numbers that shows up in panels, space is often at a premium and the dynamical range of the numbers to be displayed can be very large. Without resorting to scientific notation, it is difficult to display large number with a fixed number of decimal places. The proposal is to have method that lives in DOT/Util that would be able to round the numbers with a maximum number of decimal places (rather than a fixed number number of decimal places). In this way large number can still be displayed without occupying too much real estate. See examples in the code below.

A (local) version of this algorithm was used in charges and fields, and least squares regression.

    /**
     * Decimal adjustment of a number.
     * Function that returns (for numbers smaller than ten) a number (as a string)  with a fixed number of decimal places
     * whereas for numbers larger than ten, the number/string is returned a fixed number of significant figures that
     * is at least equal to the number of decimal places (or larger)
     *
     * @param {number} number
     * @param {Object} [options]
     * @returns {string}
     */
    function decimalAdjust( number, options ) {
      options = _.extend( {
        maxDecimalPlaces: 3
      }, options );

      // e.g. for  maxDecimalPlaces: 3
      // 9999.11 -> 9999  (numbers larger than 10^maxDecimalPlaces) are rounded to unity
      // 999.111 -> 999.1
      // 99.1111 -> 99.11
      // 9.11111 -> 9.111
      // 1.11111 -> 1.111
      // 0.11111 -> 0.111
      // 0.01111 -> 0.011
      // 0.00111 -> 0.001
      // 0.00011 -> 0.000

      // number = mantissa times 10^(exponent) where the mantissa is between 1 and 10 (or -1 to -10)
      var exponent = Math.floor( Math.log10( Math.abs( number ) ) );

      var decimalPlaces;
      if ( exponent >= options.maxDecimalPlaces ) {
        decimalPlaces = 0;
      }
      else if ( exponent > 0 ) {
        decimalPlaces = options.maxDecimalPlaces - exponent;
      }
      else {
        decimalPlaces = options.maxDecimalPlaces;
      }

      return Util.toFixed( number, decimalPlaces );
    }

[jonathanolson]

Looks great, do you want to add it to dot.Util? In a separate issue, we've discussed putting standalone functions in their own files for easier imports, any opinion on that?