Golang Rat.FloatString方法代码示例

// BigratToInt converts a *big.Rat to a *big.Int (with truncation)
func BigratToBigint(bigrat *big.Rat) *big.Int {
	int_string := bigrat.FloatString(0)
	bigint := new(big.Int)
	// no error scenario could be imagined in testing, so discard err
	fmt.Sscan(int_string, bigint)
	return bigint
}

// Prints each transaction that matches the given filters.
func PrintRegister(generalLedger []*ledger.Transaction, filterArr []string, columns int) {
	runningBalance := new(big.Rat)
	for _, trans := range generalLedger {
		for _, accChange := range trans.AccountChanges {
			inFilter := len(filterArr) == 0
			for _, filter := range filterArr {
				if strings.Contains(accChange.Name, filter) {
					inFilter = true
				}
			}
			if inFilter {
				runningBalance.Add(runningBalance, accChange.Balance)
				writtenBytes, _ := fmt.Printf("%s %s", trans.Date.Format(ledger.TransactionDateFormat), trans.Payee)
				outBalanceString := accChange.Balance.FloatString(ledger.DisplayPrecision)
				outRunningBalanceString := runningBalance.FloatString(ledger.DisplayPrecision)
				spaceCount := columns - writtenBytes - 2 - len(outBalanceString) - len(outRunningBalanceString)
				if spaceCount < 0 {
					spaceCount = 0
				}
				fmt.Printf("%s%s %s", strings.Repeat(" ", spaceCount), outBalanceString, outRunningBalanceString)
				fmt.Println("")
			}
		}
	}
}

// FloatString returns a string representation of decimal form with precision digits of precision after the decimal point and the last digit rounded.
func (this Decimal) FloatString(precision int) string {
	this.ensureValid()

	x := new(big.Rat).SetInt(this.integer)
	y := new(big.Rat).Inv(new(big.Rat).SetInt(new(big.Int).Exp(big.NewInt(int64(10)), big.NewInt(int64(this.scale)), nil)))
	z := new(big.Rat).Mul(x, y)
	return z.FloatString(precision)
}

func (r BigRat) floatString(verb byte, prec int) string {
	switch verb {
	case 'f', 'F':
		return r.Rat.FloatString(prec)
	case 'e', 'E':
		// The exponent will alway be >= 0.
		sign := ""
		var x, t big.Rat
		x.Set(r.Rat)
		if x.Sign() < 0 {
			sign = "-"
			x.Neg(&x)
		}
		t.Set(&x)
		exp := ratExponent(&x)
		ratScale(&t, exp)
		str := t.FloatString(prec + 1) // +1 because first digit might be zero.
		// Drop the decimal.
		if str[0] == '0' {
			str = str[2:]
			exp--
		} else if len(str) > 1 && str[1] == '.' {
			str = str[0:1] + str[2:]
		}
		return eFormat(verb, prec, sign, str, exp)
	case 'g', 'G':
		var x big.Rat
		x.Set(r.Rat)
		exp := ratExponent(&x)
		// Exponent could be positive or negative
		if exp < -4 || prec <= exp {
			// Use e format.
			verb -= 2 // g becomes e.
			return trimEZeros(verb, r.floatString(verb, prec-1))
		}
		// Use f format.
		// If it's got zeros right of the decimal, they count as digits in the precision.
		// If it's got digits left of the decimal, they count as digits in the precision.
		// Both are handled by adjusting prec by exp.
		str := r.floatString(verb-1, prec-exp-1) // -1 for the one digit left of the decimal.
		// Trim trailing decimals.
		point := strings.IndexByte(str, '.')
		if point > 0 {
			n := len(str)
			for str[n-1] == '0' {
				n--
			}
			str = str[:n]
			if str[n-1] == '.' {
				str = str[:n-1]
			}
		}
		return str
	default:
		Errorf("can't handle verb %c for rational", verb)
	}
	return ""
}

func String(v xdr.Int64) string {
	var f, o, r big.Rat

	f.SetInt64(int64(v))
	o.SetInt64(One)
	r.Quo(&f, &o)

	return r.FloatString(7)
}

func floatString(r *big.Rat) string {
	const prec = 50
	s := r.FloatString(prec)
	if strings.ContainsRune(s, '.') {
		s = strings.TrimRight(s, "0")
		if s[len(s)-1] == '.' {
			s += "0"
		}
	}
	return s
}

// floatString returns the string representation for a
// numeric value v in normalized floating-point format.
func floatString(v exact.Value) string {
	if exact.Sign(v) == 0 {
		return "0.0"
	}
	// x != 0

	// convert |v| into a big.Rat x
	x := new(big.Rat).SetFrac(absInt(exact.Num(v)), absInt(exact.Denom(v)))

	// normalize x and determine exponent e
	// (This is not very efficient, but also not speed-critical.)
	var e int
	for x.Cmp(ten) >= 0 {
		x.Quo(x, ten)
		e++
	}
	for x.Cmp(one) < 0 {
		x.Mul(x, ten)
		e--
	}

	// TODO(gri) Values such as 1/2 are easier to read in form 0.5
	// rather than 5.0e-1. Similarly, 1.0e1 is easier to read as
	// 10.0. Fine-tune best exponent range for readability.

	s := x.FloatString(100) // good-enough precision

	// trim trailing 0's
	i := len(s)
	for i > 0 && s[i-1] == '0' {
		i--
	}
	s = s[:i]

	// add a 0 if the number ends in decimal point
	if len(s) > 0 && s[len(s)-1] == '.' {
		s += "0"
	}

	// add exponent and sign
	if e != 0 {
		s += fmt.Sprintf("e%+d", e)
	}
	if exact.Sign(v) < 0 {
		s = "-" + s
	}

	// TODO(gri) If v is a "small" fraction (i.e., numerator and denominator
	// are just a small number of decimal digits), add the exact fraction as
	// a comment. For instance: 3.3333...e-1 /* = 1/3 */

	return s
}

// Compute 4*(1 - 1/3 + 1/5 - 1/7 + 1/9 - ...)
func main() {
	sum := big.NewRat(0, 1)
	var sumTimes4 big.Rat

	for i, sign := int64(1), int64(1); i < 10000000; i, sign = i+2, -sign {
		part := big.NewRat(sign, i)
		sum.Add(sum, part)

		if (i+1)%1000 == 0 {
			sumTimes4.Mul(big.NewRat(4, 1), sum)
			fmt.Printf("%v, %v\n", i+1, sumTimes4.FloatString(10))
		}
	}

}

// getDifficultyRatio returns the proof-of-work difficulty as a multiple of the
// minimum difficulty using the passed bits field from the header of a block.
func getDifficultyRatio(bits uint32) float64 {
	// The minimum difficulty is the max possible proof-of-work limit bits
	// converted back to a number.  Note this is not the same as the the
	// proof of work limit directly because the block difficulty is encoded
	// in a block with the compact form which loses precision.
	max := btcchain.CompactToBig(activeNetParams.powLimitBits)
	target := btcchain.CompactToBig(bits)

	difficulty := new(big.Rat).SetFrac(max, target)
	outString := difficulty.FloatString(2)
	diff, err := strconv.ParseFloat(outString, 64)
	if err != nil {
		rpcsLog.Errorf("Cannot get difficulty: %v", err)
		return 0
	}
	return diff
}

// hostcmd is the handler for the command `siac host`.
// Prints info about the host.
func hostcmd() {
	hg := new(api.HostGET)
	err := getAPI("/host", &hg)
	if err != nil {
		die("Could not fetch host settings:", err)
	}
	// convert accepting bool
	accept := yesNo(hg.AcceptingContracts)
	// convert price to SC/GB/mo
	price := new(big.Rat).SetInt(hg.Price.Big())
	price.Mul(price, big.NewRat(4320, 1e24/1e9))
	fmt.Printf(`Host info:
	Storage:      %v (%v used)
	Price:        %v SC per GB per month
	Max Duration: %v Blocks

	Contracts:           %v
	Accepting Contracts: %v
	Anticipated Revenue: %v
	Revenue:             %v
	Lost Revenue:        %v
`, filesizeUnits(hg.TotalStorage), filesizeUnits(hg.TotalStorage-hg.StorageRemaining),
		price.FloatString(3), hg.MaxDuration, hg.NumContracts, accept,
		hg.AnticipatedRevenue, hg.Revenue, hg.LostRevenue)

	// display more info if verbose flag is set
	if !hostVerbose {
		return
	}
	fmt.Printf(`
	Net Address: %v
	Unlock Hash: %v
	(NOT a wallet address!)

RPC Stats:
	Error Calls:        %v
	Unrecognized Calls: %v
	Download Calls:     %v
	Renew Calls:        %v
	Revise Calls:       %v
	Settings Calls:     %v
	Upload Calls:       %v
`, hg.NetAddress, hg.UnlockHash, hg.RPCErrorCalls, hg.RPCUnrecognizedCalls, hg.RPCDownloadCalls,
		hg.RPCRenewCalls, hg.RPCReviseCalls, hg.RPCSettingsCalls, hg.RPCUploadCalls)
}

// Prints out account balances formated to a windows of a width of columns.
// Only shows accounts with names less than or equal to the given depth.
func PrintBalances(accountList []*ledger.Account, printZeroBalances bool, depth, columns int) {
	overallBalance := new(big.Rat)
	for _, account := range accountList {
		accDepth := len(strings.Split(account.Name, ":"))
		if accDepth == 1 {
			overallBalance.Add(overallBalance, account.Balance)
		}
		if (printZeroBalances || account.Balance.Sign() != 0) && (depth < 0 || accDepth <= depth) {
			outBalanceString := account.Balance.FloatString(ledger.DisplayPrecision)
			spaceCount := columns - len(account.Name) - len(outBalanceString)
			fmt.Printf("%s%s%s\n", account.Name, strings.Repeat(" ", spaceCount), outBalanceString)
		}
	}
	fmt.Println(strings.Repeat("-", columns))
	outBalanceString := overallBalance.FloatString(ledger.DisplayPrecision)
	spaceCount := columns - len(outBalanceString)
	fmt.Printf("%s%s\n", strings.Repeat(" ", spaceCount), outBalanceString)
}

func Parse(v string) (xdr.Int64, error) {
	var f, o, r big.Rat

	_, ok := f.SetString(v)
	if !ok {
		return xdr.Int64(0), fmt.Errorf("cannot parse amount: %s", v)
	}

	o.SetInt64(One)
	r.Mul(&f, &o)

	is := r.FloatString(0)
	i, err := strconv.ParseInt(is, 10, 64)
	if err != nil {
		return xdr.Int64(0), err
	}
	return xdr.Int64(i), nil
}

//"Pell Equation"
func main() {
	starttime := time.Now()

	total := 0
	for rad := 2; rad <= 100; rad++ {

		if !isSquare(rad) {

			convergentList := make([]int, 1)

			test := frac{a: 0, b: 1, R: rad, d: 1}
			n := 0

			n, test = nextFrac(test)

			convergentList[0] = n

			for i := 0; i < 200; i++ {
				n, test = nextFrac(test)
				convergentList = append(convergentList, n)

			}

			fLength := len(convergentList) - 1

			p, q := ctdFrac(convergentList[:fLength])

			var r big.Rat

			r.SetString(p + "/" + q)

			deciString := r.FloatString(105) //A bit too long in order to avoid rounding

			total += sumDigits(deciString[:101]) //The extra 1 is the decimal point
		}
	}

	fmt.Println(total)

	fmt.Println("Elapsed time:", time.Since(starttime))

}

func hoststatuscmd() {
	info := new(modules.HostInfo)
	err := getAPI("/host/status", info)
	if err != nil {
		fmt.Println("Could not fetch host settings:", err)
		return
	}
	// convert price to SC/GB/mo
	price := new(big.Rat).SetInt(info.Price.Big())
	price.Mul(price, big.NewRat(4320, 1e24/1e9))
	fmt.Printf(`Host settings:
Storage:      %v (%v used)
Price:        %v SC per GB per month
Collateral:   %v
Max Filesize: %v
Max Duration: %v
Contracts:    %v
`, filesizeUnits(info.TotalStorage), filesizeUnits(info.TotalStorage-info.StorageRemaining),
		price.FloatString(3), info.Collateral, info.MaxFilesize, info.MaxDuration, info.NumContracts)
}

func f1() {
	max := 1
	ii := 2
	for i := 2; i < 1000; i++ {
		r := new(big.Rat)
		r.SetString("1/" + strconv.Itoa(i))
		s := r.FloatString(10000)[2:9999]
		//s = strings.TrimLeft(s, "0")
		//fmt.Println(s)

		v := dup(&s)
		d := len(v)
		if max < d {
			max = d
			ii = i
			//fmt.Println(i, d, s, v)
		}
	}

	fmt.Println(ii, max)
}