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{{numeral systems}} | |||
A '''negative base''' (or negative [[radix]]) may be used to construct a [[non-standard positional numeral system]]. Like other place-value systems, each position holds multiples of the appropriate power of the system's base; but that base is negative—that is to say, the base <math>\scriptstyle b</math> is equal to <math>\scriptstyle -r</math> for some natural number <math>\scriptstyle r</math> (''r ≥ 2''). | |||
Negative-base systems can accommodate all the same numbers as standard place-value systems, but both positive and negative numbers are represented without the use of a [[minus sign]] (or, in computer representation, a [[sign bit]]); this advantage is countered by an increased complexity of arithmetic operations. The need to store the information normally contained by a negative sign often results in a negative-base number being one digit longer than its positive-base equivalent. | |||
The common names for negative-base positional numeral systems are formed by [[prefix (linguistics)|prefixing]] ''nega-'' to the name of the corresponding positive-base system; for example, '''negadecimal''' (base −10) corresponds to [[decimal]] (base 10), '''negaternary''' (base −3) to [[ternary numeral system|ternary]] (base 3), and '''negabinary''' (base −2) to [[binary numeral system|binary]] (base 2).<ref>{{harvnb|Knuth|1998}} and [[#WeissteinNegadecimal|Weisstein]] each refer to the negadecimal system. In the index {{harvnb|Knuth|1998}} refers to the negabinary system, as does [[#WeissteinNegabinary|Weisstein]]. The negaternary system is discussed briefly in {{Citation | last1=Petkovšek | first1=Marko | author1-link=Marko Petkovšek | title=Ambiguous numbers are dense | doi=10.2307/2324393 | mr=1048915 | year=1990 | journal=[[American Mathematical Monthly|The American Mathematical Monthly]] | issn=0002-9890 | volume=97 | issue=5 | pages=408–411}}.</ref> | |||
==Example== | |||
Consider what is meant by the representation ''12,243'' in the negadecimal system, whose base <math>\scriptstyle b</math> is −10: | |||
{| class="wikitable" | |||
|- | |||
|align="center"| multiples of <math>\scriptstyle b^4</math> <br> (i.e., 10,000) | |||
|align="center"| multiples of <math>\scriptstyle b^3</math> <br> (i.e., −1,000) | |||
|align="center"| multiples of <math>\scriptstyle b^2</math> <br> (i.e., 100) | |||
|align="center"| multiples of <math>\scriptstyle b^1</math> <br> (i.e., −10) | |||
|align="center"| multiples of <math>\scriptstyle b^0</math> <br> (i.e., 1) | |||
|- | |||
|align="center"| 1 | |||
|align="center"| 2 | |||
|align="center"| 2 | |||
|align="center"| 4 | |||
|align="center"| 3 | |||
|- | |||
|} | |||
Since 10,000 + (−2,000) + 200 + (−40) + 3 = 8,163, the representation ''12,243'' in negadecimal notation is equivalent to ''8,163'' in decimal notation. | |||
==History== | |||
Negative numerical bases were first considered by [[Vittorio Grünwald]] in his work ''Giornale di Matematiche di Battaglini'', published in 1885. Grünwald gave algorithms for performing addition, subtraction, multiplication, division, root extraction, divisibility tests, and radix conversion. Negative bases were later independently rediscovered by [[Aubrey J. Kempner|A. J. Kempner]] in 1936 and [[Zdzisław Pawlak]] and A. Wakulicz in 1959{{Citation needed|date=May 2012}}. | |||
Negabinary was implemented in the early [[Poland|Polish]] computer [[BINEG]], built 1957–59, based on ideæ by Z. Pawlak and A. Lazarkiewicz from the [[Mathematical Institute]] in [[Warsaw]].<ref>[http://chc60.fgcu.edu/images/articles/Marczynski.pdf Marczynski, R. W., "The First Seven Years of Polish Computing"], IEEE Annals of the History of Computing, Vol. 2, No 1, January 1980</ref> Implementations since then have been rare. | |||
==Notation and use== | |||
Denoting the base as <math>-r</math>, every [[integer]] <math>a</math> can be written uniquely as | |||
:<math>a = \sum_{i=0}^{n}d_{i}(-r)^{i}</math> | |||
where each digit <math>\scriptstyle d_k</math> is an integer from 0 to <math>\scriptstyle r - 1</math> and the leading digit <math>\scriptstyle d_n</math> is <math>\scriptstyle > 0</math> (unless <math>\scriptstyle n=0</math>). The base <math>\scriptstyle -r</math> expansion of <math>\scriptstyle a</math> is then given by the string <math>\scriptstyle d_n d_{n-1} \ldots d_1 d_0</math>. | |||
Negative-base systems may thus be compared to [[signed-digit representation]]s, such as [[balanced ternary]], where the radix is positive but the digits are taken from a partially negative range. | |||
Some numbers have the same representation in base <math>\scriptstyle -r</math> as in base <math>r</math>. For example, the numbers from 100 to 109 have the same representations in decimal and negadecimal. Similarly, | |||
:<math>17=2^4+2^0=(-2)^4+(-2)^0</math> | |||
and is represented by 10001 in binary and 10001 in negabinary. | |||
Some numbers with their expansions in a number of positive and corresponding negative bases are: | |||
{|class="wikitable" style="margin: 1em auto 1em auto; text-align: right;" | |||
! Decimal !! Negadecimal !! Binary !! Negabinary !! Ternary !! Negaternary | |||
|- | |||
| −15 || 25 || −1111 || 110001 || −120 || 1220 | |||
|- | |||
| : || : || : || : || : || : | |||
|- | |||
| −5 || 15 || −101 || 1111 || −12 || 21 | |||
|- | |||
| −4 || 16 || −100 || 1100 || −11 || 22 | |||
|- | |||
| −3 || 17 || −11 || 1101 || −10 || 10 | |||
|- | |||
| −2 || 18 || −10 || 10 || −2 || 11 | |||
|- | |||
| −1 || 19 || −1 || 11 || −1 || 12 | |||
|- | |||
| 0 || 0 || 0 || 0 || 0 || 0 | |||
|- | |||
| 1 || 1 || 1 || 1 || 1 || 1 | |||
|- | |||
| 2 || 2 || 10 || 110 || 2 || 2 | |||
|- | |||
| 3 || 3 || 11 || 111 || 10 || 120 | |||
|- | |||
| 4 || 4 || 100 || 100 || 11 || 121 | |||
|- | |||
| 5 || 5 || 101 || 101 || 12 || 122 | |||
|- | |||
| 6 || 6 || 110 || 11010 || 20 || 110 | |||
|- | |||
| 7 || 7 || 111 || 11011 || 21 || 111 | |||
|- | |||
| 8 || 8 || 1000 || 11000 || 22 || 112 | |||
|- | |||
| 9 || 9 || 1001 || 11001 || 100 || 100 | |||
|- | |||
| 10 || 190 || 1010 || 11110 || 101 || 101 | |||
|- | |||
| 11 || 191 || 1011 || 11111 || 102 || 102 | |||
|- | |||
| 12 || 192 || 1100 || 11100 || 110 || 220 | |||
|- | |||
| 13 || 193 || 1101 || 11101 || 111 || 221 | |||
|- | |||
| 14 || 194 || 1110 || 10010 || 112 || 222 | |||
|- | |||
| 15 || 195 || 1111 || 10011 || 120 || 210 | |||
|- | |||
| 16 || 195 || 10000 || 10000 || 121 || 211 | |||
|- | |||
| 17 || 197 || 10001 || 10001 || 122 || 212 | |||
|} | |||
Note that the base <math>\scriptstyle -r</math> expansions of negative integers have an [[even number]] of digits, while the base <math>\scriptstyle -r</math> expansions of the non-negative integers have an [[odd number]] of digits. | |||
==Calculation== | |||
The base <math>\scriptstyle -r</math> expansion of a number can be found by repeated division by <math>\scriptstyle -r</math>, recording the non-negative remainders of <math>\scriptstyle 0, 1,\ldots r-1</math>, and concatenating those remainders, starting with the last. Note that if <math>\scriptstyle a / b = c</math>, remainder <math>d</math>, then <math>\scriptstyle bc + d = a</math>. For example, in negaternary: | |||
:<math>\begin{align} | |||
146 & ~/~ -3 = & -48, & ~\mbox{remainder}~ 2 \\ | |||
-48 & ~/~ -3 = & 16, & ~\mbox{remainder}~ 0 \\ | |||
16 & ~/~ -3 = & -5, & ~\mbox{remainder}~ 1 \\ | |||
-5 & ~/~ -3 = & 2, & ~\mbox{remainder}~ 1 \\ | |||
2 & ~/~ -3 = & 0, & ~\mbox{remainder}~ 2 \\ | |||
\end{align}</math> | |||
Therefore, the negaternary expansion of 146 is 21,102. | |||
Note that in most [[programming languages]], the result (in integer arithmetic) of dividing a negative number by a negative number is rounded towards 0, usually leaving a negative remainder. In such a case we have <math>\scriptstyle a = (-r)c + d = (-r)c + d - r + r = (-r)(c + 1) + (d + r)</math>. Because <math>\scriptstyle |d| < r</math>, <math>\scriptstyle (d + r)</math> is the positive remainder. Therefore, to get the correct result in such case, computer implementations of the above algorithm should add 1 and <math>r</math> to the quotient and remainder respectively (shown below in the [[Python (programming language)|Python]] programming language): | |||
<source lang="python"> | |||
def negaternary(i): | |||
digits = '' | |||
if not i: | |||
digits = '0' | |||
else: | |||
while i != 0: | |||
i, remainder = divmod(i, -3) | |||
if remainder < 0: | |||
i, remainder = i + 1, remainder + 3 | |||
digits = str(remainder)+ digits | |||
return digits | |||
</source> | |||
C# implementation: | |||
<source lang="csharp"> | |||
static string negatenary(int value) | |||
{ | |||
string result = string.Empty; | |||
while (value != 0) | |||
{ | |||
int remainder = value % -3; | |||
value = value / -3; | |||
if (remainder < 0) | |||
{ | |||
remainder += 3; | |||
value += 1; | |||
} | |||
result = remainder.ToString() + result; | |||
} | |||
return result; | |||
} | |||
</source> | |||
Common Lisp implementation: | |||
<source lang="lisp"> | |||
(defun negaternary (i) | |||
(if (zerop i) | |||
"0" | |||
(let ((digits "") | |||
(rem 0)) | |||
(loop while (not (zerop i)) do | |||
(progn | |||
(multiple-value-setq (i rem) (truncate i -3)) | |||
(when (minusp rem) | |||
(incf i) | |||
(incf rem 3)) | |||
(setf digits (concatenate 'string (write-to-string rem) digits)))) | |||
digits))) | |||
</source> | |||
==Arithmetic operations== | |||
The following describes the arithmetic operations for negabinary; calculations in larger bases are similar. | |||
===Addition=== | |||
To add two negabinary numbers, start with a carry of 0, and, starting from the [[least significant bit]]s, add the bits of the two numbers plus the carry. The resulting number is then looked up in the following table to get the bit to write down as result, and the next carry: | |||
{| class="wikitable" | |||
! Number !! Bit !! Carry !! Comment | |||
|- | |||
| −2 || 0 || 1 || −2 occurs only during subtraction. | |||
|- | |||
| −1 || 1 || 1 || | |||
|- | |||
| 0 || 0 || 0 || | |||
|- | |||
| 1 || 1 || 0 || | |||
|- | |||
| 2 || 0 || −1 || | |||
|- | |||
| 3 || 1 || −1 || 3 occurs only during addition. | |||
|} | |||
The second row of this table, for instance, expresses the fact that '''−1''' = '''1''' + '''1''' × −2; the fifth row says '''2''' = '''0''' + '''−1''' × −2; etc. | |||
As an example, to add 1010101 (1 + 4 + 16 + 64 = 85) and 1110100 (4 + 16 − 32 + 64 = 52), | |||
carry: 1 −1 0 −1 1 −1 0 0 0 | |||
first number: 1 0 1 0 1 0 1 | |||
second number: 1 1 1 0 1 0 0 + | |||
-------------------------- | |||
number: 1 −1 2 0 3 −1 2 0 1 | |||
bit (result): 1 1 0 0 1 1 0 0 1 | |||
carry: 0 1 −1 0 −1 1 −1 0 0 | |||
so the result is 110011001 (1 − 8 + 16 − 128 + 256 = 137). | |||
==== Another Method ==== | |||
While adding two negabinary numbers, every time a carry is generated an extra carry should be propagated to next bit. | |||
Consider same example as above | |||
extra carry: 1 1 0 1 0 0 0 | |||
carry: 1 0 1 1 0 1 0 0 0 | |||
first number: 1 0 1 0 1 0 1 | |||
second number: 1 1 1 0 1 0 0 + | |||
-------------------------- | |||
Answer: 1 1 0 0 1 1 0 0 1 | |||
===Subtraction=== | |||
To subtract, multiply each bit of the second number by −1, and add the numbers, using the same table as above. | |||
As an example, to compute 1101001 (1 − 8 − 32 + 64 = 25) minus 1110100 (4 + 16 − 32 + 64 = 52), | |||
carry: 0 1 −1 1 0 0 0 | |||
first number: 1 1 0 1 0 0 1 | |||
second number: −1 −1 −1 0 −1 0 0 + | |||
-------------------- | |||
number: 0 1 −2 2 −1 0 1 | |||
bit (result): 0 1 0 0 1 0 1 | |||
carry: 0 0 1 −1 1 0 0 | |||
so the result is 100101 (1 + 4 −32 = −27). | |||
To negate a number, compute 0 minus the number. | |||
===Multiplication and division=== | |||
Shifting to the left multiplies by −2, shifting to the right divides by −2. | |||
To multiply, multiply like normal [[decimal]] or [[binary numeral system|binary]] numbers, but using the negabinary rules for adding the carry, when adding the numbers. | |||
first number: 1 1 1 0 1 1 0 | |||
second number: 1 0 1 1 0 1 1 * | |||
------------------------------------- | |||
1 1 1 0 1 1 0 | |||
1 1 1 0 1 1 0 | |||
1 1 1 0 1 1 0 | |||
1 1 1 0 1 1 0 | |||
1 1 1 0 1 1 0 + | |||
------------------------------------- | |||
carry: 0 −1 0 −1 −1 −1 −1 −1 0 −1 0 0 | |||
number: 1 0 2 1 2 2 2 3 2 0 2 1 0 | |||
bit (result): 1 0 0 1 0 0 0 1 0 0 0 1 0 | |||
carry: 0 −1 0 −1 −1 −1 −1 −1 0 −1 0 0 | |||
For each column, add ''carry'' to ''number'', and divide the sum by −2, to get the new ''carry'', and the resulting bit as the remainder. | |||
<!-- | |||
(Todo: Division by arbitrary numbers?) | |||
--><!-- | |||
"To be written things", like below, better be written. Empty sections are ugly. | |||
===Divisibility tests=== | |||
To be written. | |||
===Root extraction=== | |||
To be written. | |||
--> | |||
==Fractional numbers== | |||
Base <math>\scriptstyle -r</math> representation may of course be carried beyond the [[radix point]], allowing the representation of non-integral numbers. | |||
As with positive-base systems, terminating representations correspond to fractions where the denominator is a power of the base; repeating representations correspond to other rationals, and for the same reason. | |||
===Non-unique representations=== | |||
Unlike positive-base systems, where integers and terminating fractions have non-unique representations (for example, in decimal [[0.999… = 1]]) in negative-base systems the integers have only a single representation. However, there do exist rationals with non-unique representations; for example, in negaternary, | |||
: <math>0.(02)\ldots_{(-3)} = \frac{1}{4} = 1.(20)\ldots_{(-3)}</math>. | |||
Such non-unique representations can be found by considering the largest and smallest possible representations with integral parts 0 and 1 respectively, and then noting that they are equal. (Indeed, this works with any integral-base system.) The rationals thus non-uniquely expressible are those of form | |||
: <math>\frac{ar + 1}{b(r + 1)}</math>. | |||
== Imaginary base == | |||
{{main|Complex base systems}} | |||
Just as using a negative base allows the representation of negative numbers without an explicit negative sign, using an [[imaginary number|imaginary]] base allows the representation of [[Gaussian integer]]s. [[Donald Knuth]] proposed the [[quater-imaginary base]] (base 2i) in 1955.<ref>D. Knuth. The Art of Computer Programming. Volume 2, 3rd Edition. Addison-Wesley. pp. 205, "Positional Number Systems"</ref> | |||
Imaginary-base arithmetic is not much different from negative-base arithmetic, since an imaginary-base number may be considered as the interleave of its real and imaginary parts; using [[INTERCAL]]-72 notation, | |||
: ''x''<sub>(2i)</sub> + (2''i'')''y''<sub>(2i)</sub> = ''x''<sub>(2i)</sub> ¢ ''y''<sub>(2i)</sub>. | |||
== See also == | |||
* [[Quater-imaginary base]] | |||
* [[Binary numeral system|Binary]] | |||
* [[Balanced ternary]] | |||
* [[Numeral system]]s | |||
== Notes == | |||
<references/> | |||
==References== | |||
* Vittorio Grünwald. ''Giornale di Matematiche di Battaglini'' (1885), 203-221, 367 | |||
* A. J. Kempner. (1936), 610-617 | |||
* Z. Pawlak and A. Wakulicz ''Bulletin de l'Academie Polonaise des Scienses'', Classe III, 5 (1957), 233-236; Serie des sciences techniques 7 (1959), 713-721 | |||
* L. Wadel ''IRE Transactions EC-6'' 1957, 123 | |||
* N. M. Blachman, ''Communications of the ACM'' (1961), 257 | |||
* IEEE Transactions 1963, 274-276 | |||
* ''Computer Design'' May 1967, 52-63 | |||
* R. W. Marczynski, ''Annotated History of Computing'', 1980, 37-48 | |||
* {{citation|first=Donald|last=Knuth|title=[[The Art of Computer Programming]], Volume 2|year=1998|edition=3rd|pages=204–205}}. | |||
* {{anchor|WeissteinNegabinary}} {{mathworld|title=Negabinary|urlname=Negabinary}} | |||
* {{anchor|WeissteinNegadecimal}} {{mathworld|title=Negadecimal|urlname=Negadecimal}} | |||
[[Category:Non-standard positional numeral systems]] | |||
[[Category:Computer arithmetic]] |
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A negative base (or negative radix) may be used to construct a non-standard positional numeral system. Like other place-value systems, each position holds multiples of the appropriate power of the system's base; but that base is negative—that is to say, the base is equal to for some natural number (r ≥ 2).
Negative-base systems can accommodate all the same numbers as standard place-value systems, but both positive and negative numbers are represented without the use of a minus sign (or, in computer representation, a sign bit); this advantage is countered by an increased complexity of arithmetic operations. The need to store the information normally contained by a negative sign often results in a negative-base number being one digit longer than its positive-base equivalent.
The common names for negative-base positional numeral systems are formed by prefixing nega- to the name of the corresponding positive-base system; for example, negadecimal (base −10) corresponds to decimal (base 10), negaternary (base −3) to ternary (base 3), and negabinary (base −2) to binary (base 2).[1]
Example
Consider what is meant by the representation 12,243 in the negadecimal system, whose base is −10:
multiples of (i.e., 10,000) |
multiples of (i.e., −1,000) |
multiples of (i.e., 100) |
multiples of (i.e., −10) |
multiples of (i.e., 1) |
1 | 2 | 2 | 4 | 3 |
Since 10,000 + (−2,000) + 200 + (−40) + 3 = 8,163, the representation 12,243 in negadecimal notation is equivalent to 8,163 in decimal notation.
History
Negative numerical bases were first considered by Vittorio Grünwald in his work Giornale di Matematiche di Battaglini, published in 1885. Grünwald gave algorithms for performing addition, subtraction, multiplication, division, root extraction, divisibility tests, and radix conversion. Negative bases were later independently rediscovered by A. J. Kempner in 1936 and Zdzisław Pawlak and A. Wakulicz in 1959Potter or Ceramic Artist Truman Bedell from Rexton, has interests which include ceramics, best property developers in singapore developers in singapore and scrabble. Was especially enthused after visiting Alejandro de Humboldt National Park..
Negabinary was implemented in the early Polish computer BINEG, built 1957–59, based on ideæ by Z. Pawlak and A. Lazarkiewicz from the Mathematical Institute in Warsaw.[2] Implementations since then have been rare.
Notation and use
Denoting the base as , every integer can be written uniquely as
where each digit is an integer from 0 to and the leading digit is (unless ). The base expansion of is then given by the string .
Negative-base systems may thus be compared to signed-digit representations, such as balanced ternary, where the radix is positive but the digits are taken from a partially negative range.
Some numbers have the same representation in base as in base . For example, the numbers from 100 to 109 have the same representations in decimal and negadecimal. Similarly,
and is represented by 10001 in binary and 10001 in negabinary.
Some numbers with their expansions in a number of positive and corresponding negative bases are:
Decimal | Negadecimal | Binary | Negabinary | Ternary | Negaternary |
---|---|---|---|---|---|
−15 | 25 | −1111 | 110001 | −120 | 1220 |
: | : | : | : | : | : |
−5 | 15 | −101 | 1111 | −12 | 21 |
−4 | 16 | −100 | 1100 | −11 | 22 |
−3 | 17 | −11 | 1101 | −10 | 10 |
−2 | 18 | −10 | 10 | −2 | 11 |
−1 | 19 | −1 | 11 | −1 | 12 |
0 | 0 | 0 | 0 | 0 | 0 |
1 | 1 | 1 | 1 | 1 | 1 |
2 | 2 | 10 | 110 | 2 | 2 |
3 | 3 | 11 | 111 | 10 | 120 |
4 | 4 | 100 | 100 | 11 | 121 |
5 | 5 | 101 | 101 | 12 | 122 |
6 | 6 | 110 | 11010 | 20 | 110 |
7 | 7 | 111 | 11011 | 21 | 111 |
8 | 8 | 1000 | 11000 | 22 | 112 |
9 | 9 | 1001 | 11001 | 100 | 100 |
10 | 190 | 1010 | 11110 | 101 | 101 |
11 | 191 | 1011 | 11111 | 102 | 102 |
12 | 192 | 1100 | 11100 | 110 | 220 |
13 | 193 | 1101 | 11101 | 111 | 221 |
14 | 194 | 1110 | 10010 | 112 | 222 |
15 | 195 | 1111 | 10011 | 120 | 210 |
16 | 195 | 10000 | 10000 | 121 | 211 |
17 | 197 | 10001 | 10001 | 122 | 212 |
Note that the base expansions of negative integers have an even number of digits, while the base expansions of the non-negative integers have an odd number of digits.
Calculation
The base expansion of a number can be found by repeated division by , recording the non-negative remainders of , and concatenating those remainders, starting with the last. Note that if , remainder , then . For example, in negaternary:
Therefore, the negaternary expansion of 146 is 21,102.
Note that in most programming languages, the result (in integer arithmetic) of dividing a negative number by a negative number is rounded towards 0, usually leaving a negative remainder. In such a case we have . Because , is the positive remainder. Therefore, to get the correct result in such case, computer implementations of the above algorithm should add 1 and to the quotient and remainder respectively (shown below in the Python programming language):
def negaternary(i):
digits = ''
if not i:
digits = '0'
else:
while i != 0:
i, remainder = divmod(i, -3)
if remainder < 0:
i, remainder = i + 1, remainder + 3
digits = str(remainder)+ digits
return digits
C# implementation:
static string negatenary(int value)
{
string result = string.Empty;
while (value != 0)
{
int remainder = value % -3;
value = value / -3;
if (remainder < 0)
{
remainder += 3;
value += 1;
}
result = remainder.ToString() + result;
}
return result;
}
Common Lisp implementation:
(defun negaternary (i)
(if (zerop i)
"0"
(let ((digits "")
(rem 0))
(loop while (not (zerop i)) do
(progn
(multiple-value-setq (i rem) (truncate i -3))
(when (minusp rem)
(incf i)
(incf rem 3))
(setf digits (concatenate 'string (write-to-string rem) digits))))
digits)))
Arithmetic operations
The following describes the arithmetic operations for negabinary; calculations in larger bases are similar.
Addition
To add two negabinary numbers, start with a carry of 0, and, starting from the least significant bits, add the bits of the two numbers plus the carry. The resulting number is then looked up in the following table to get the bit to write down as result, and the next carry:
Number | Bit | Carry | Comment |
---|---|---|---|
−2 | 0 | 1 | −2 occurs only during subtraction. |
−1 | 1 | 1 | |
0 | 0 | 0 | |
1 | 1 | 0 | |
2 | 0 | −1 | |
3 | 1 | −1 | 3 occurs only during addition. |
The second row of this table, for instance, expresses the fact that −1 = 1 + 1 × −2; the fifth row says 2 = 0 + −1 × −2; etc.
As an example, to add 1010101 (1 + 4 + 16 + 64 = 85) and 1110100 (4 + 16 − 32 + 64 = 52),
carry: 1 −1 0 −1 1 −1 0 0 0 first number: 1 0 1 0 1 0 1 second number: 1 1 1 0 1 0 0 + -------------------------- number: 1 −1 2 0 3 −1 2 0 1 bit (result): 1 1 0 0 1 1 0 0 1 carry: 0 1 −1 0 −1 1 −1 0 0
so the result is 110011001 (1 − 8 + 16 − 128 + 256 = 137).
Another Method
While adding two negabinary numbers, every time a carry is generated an extra carry should be propagated to next bit. Consider same example as above
extra carry: 1 1 0 1 0 0 0 carry: 1 0 1 1 0 1 0 0 0 first number: 1 0 1 0 1 0 1 second number: 1 1 1 0 1 0 0 + -------------------------- Answer: 1 1 0 0 1 1 0 0 1
Subtraction
To subtract, multiply each bit of the second number by −1, and add the numbers, using the same table as above.
As an example, to compute 1101001 (1 − 8 − 32 + 64 = 25) minus 1110100 (4 + 16 − 32 + 64 = 52),
carry: 0 1 −1 1 0 0 0 first number: 1 1 0 1 0 0 1 second number: −1 −1 −1 0 −1 0 0 + -------------------- number: 0 1 −2 2 −1 0 1 bit (result): 0 1 0 0 1 0 1 carry: 0 0 1 −1 1 0 0
so the result is 100101 (1 + 4 −32 = −27).
To negate a number, compute 0 minus the number.
Multiplication and division
Shifting to the left multiplies by −2, shifting to the right divides by −2.
To multiply, multiply like normal decimal or binary numbers, but using the negabinary rules for adding the carry, when adding the numbers.
first number: 1 1 1 0 1 1 0 second number: 1 0 1 1 0 1 1 * ------------------------------------- 1 1 1 0 1 1 0 1 1 1 0 1 1 0 1 1 1 0 1 1 0 1 1 1 0 1 1 0 1 1 1 0 1 1 0 + ------------------------------------- carry: 0 −1 0 −1 −1 −1 −1 −1 0 −1 0 0 number: 1 0 2 1 2 2 2 3 2 0 2 1 0 bit (result): 1 0 0 1 0 0 0 1 0 0 0 1 0 carry: 0 −1 0 −1 −1 −1 −1 −1 0 −1 0 0
For each column, add carry to number, and divide the sum by −2, to get the new carry, and the resulting bit as the remainder.
Fractional numbers
Base representation may of course be carried beyond the radix point, allowing the representation of non-integral numbers.
As with positive-base systems, terminating representations correspond to fractions where the denominator is a power of the base; repeating representations correspond to other rationals, and for the same reason.
Non-unique representations
Unlike positive-base systems, where integers and terminating fractions have non-unique representations (for example, in decimal 0.999… = 1) in negative-base systems the integers have only a single representation. However, there do exist rationals with non-unique representations; for example, in negaternary,
Such non-unique representations can be found by considering the largest and smallest possible representations with integral parts 0 and 1 respectively, and then noting that they are equal. (Indeed, this works with any integral-base system.) The rationals thus non-uniquely expressible are those of form
Imaginary base
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Just as using a negative base allows the representation of negative numbers without an explicit negative sign, using an imaginary base allows the representation of Gaussian integers. Donald Knuth proposed the quater-imaginary base (base 2i) in 1955.[3]
Imaginary-base arithmetic is not much different from negative-base arithmetic, since an imaginary-base number may be considered as the interleave of its real and imaginary parts; using INTERCAL-72 notation,
- x(2i) + (2i)y(2i) = x(2i) ¢ y(2i).
See also
Notes
- ↑ Template:Harvnb and Weisstein each refer to the negadecimal system. In the index Template:Harvnb refers to the negabinary system, as does Weisstein. The negaternary system is discussed briefly in Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.
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15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.
To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010. - ↑ Marczynski, R. W., "The First Seven Years of Polish Computing", IEEE Annals of the History of Computing, Vol. 2, No 1, January 1980
- ↑ D. Knuth. The Art of Computer Programming. Volume 2, 3rd Edition. Addison-Wesley. pp. 205, "Positional Number Systems"
References
- Vittorio Grünwald. Giornale di Matematiche di Battaglini (1885), 203-221, 367
- A. J. Kempner. (1936), 610-617
- Z. Pawlak and A. Wakulicz Bulletin de l'Academie Polonaise des Scienses, Classe III, 5 (1957), 233-236; Serie des sciences techniques 7 (1959), 713-721
- L. Wadel IRE Transactions EC-6 1957, 123
- N. M. Blachman, Communications of the ACM (1961), 257
- IEEE Transactions 1963, 274-276
- Computer Design May 1967, 52-63
- R. W. Marczynski, Annotated History of Computing, 1980, 37-48
- Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.
Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.
In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.
Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region
Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.
15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.
To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010. <WeissteinNegabinary>...</WeissteinNegabinary>
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