+ // This is deceptively simple. The actual algorithm comes from:
+ //
+ // Max allowed length = p + 4
+ // where 4 comes from 'e+n' and '.'.
+ //
+ // Length of fixed format = 2 + y + p
+ // where 2 comes from '0.' and y = # of leading zeroes.
+ //
+ // Equating the two and solving for y yields y = 2, or 0.00xxxx which is
+ // 1.0e-3.
+ //
+ // Since the behavior of toPrecision() is identical for larger numbers, we
+ // don't have to worry about the other bound.
+ //
+ // Finally, the argument for toExponential() is the number of trailing digits,
+ // so we take off 1 for the value before the '.'.
+ return (Math.abs(x) < 1.0e-3 && x != 0.0) ?
+ x.toExponential(p - 1) : x.toPrecision(p);
+};
+
+/**
+ * @private
+ * Return a string version of a number. This respects the digitsAfterDecimal
+ * and maxNumberWidth options.
+ * @param {Number} x The number to be formatted
+ * @param {Dygraph} g The dygraph object
+ */
+Dygraph.numberFormatter = function(x, g) {
+ var sigFigs = g.attr_('sigFigs');
+
+ if (sigFigs !== null) {
+ // User has opted for a fixed number of significant figures.
+ return Dygraph.floatFormat(x, sigFigs);
+ }
+
+ var digits = g.attr_('digitsAfterDecimal');
+ var maxNumberWidth = g.attr_('maxNumberWidth');
+
+ // switch to scientific notation if we underflow or overflow fixed display.
+ if (x !== 0.0 &&
+ (Math.abs(x) >= Math.pow(10, maxNumberWidth) ||
+ Math.abs(x) < Math.pow(10, -digits))) {
+ return x.toExponential(digits);
+ } else {
+ return '' + Dygraph.round_(x, digits);
+ }
+};
+
+/**
+ * @private
+ * Converts '9' to '09' (useful for dates)
+ */