if digits == -1 {
				digits = 6
			}
		}

		// Buffer pre-allocated with enough room for
		// exponent notations of the form "e+123" or "p-1023".
		var tailBuf [6]byte
		tail := tailBuf[:0]

		hasDecimalPoint := false
		sawNonzeroDigit := false
		// Starting from i = 1 to skip sign at num[0].
		for i := 1; i < len(num); i++ {
			switch num[i] {
			case '.':

	// span in any alignment.
	minBands := int((int64(window) + c.bandDur - 1) / c.bandDur)
	maxBands := int((int64(window) + 2*(c.bandDur-1)) / c.bandDur)
	if window > 1 && maxBands < 2 {
		panic("maxBands < 2")
	}
	tailDur := int64(window) % c.bandDur
	nUtil := len(c.bands) - maxBands + 1
	if nUtil < 0 {
		nUtil = 0
	}
	bandU := make([]bandUtil, nUtil)
	for i := range bandU {