Modulo operation

In computing, the modulo operation returns the remainder or signed remainder of a division, after one number is divided by another (called the modulus of the operation).

Quotient (

q

) and remainder (

r

) as functions of dividend (

a

), using different algorithms

Given two positive numbers $a$ and $n$ , $a$ modulo $n$ (abbreviated as $a mod n$ ) is the remainder of the Euclidean division of $a$ by $n$ , where $a$ is the dividend and $n$ is the divisor.[1] The modulo operation is to be distinguished from the symbol $mod$ , which refers to the modulus[2] (or divisor) one is operating from.

For example, the expression "5 mod 2" would evaluate to 1, because 5 divided by 2 has a quotient of 2 and a remainder of 1, while "9 mod 3" would evaluate to 0, because the division of 9 by 3 has a quotient of 3 and a remainder of 0; there is nothing to subtract from 9 after multiplying 3 times 3.

(Here, notice that doing division with a calculator will not show the result of the modulo operation, and that the quotient will be expressed as a decimal fraction if a non-zero remainder is involved.)

Although typically performed with $a$ and $n$ both being integers, many computing systems now allow other types of numeric operands. The range of numbers for an integer modulo of $n$ is 0 to $n - 1$ inclusive ( $a$ mod 1 is always 0; $a mod 0$ is undefined, possibly resulting in a division by zero error in some programming languages). See modular arithmetic for an older and related convention applied in number theory.

When exactly one of $a$ or $n$ is negative, the naive definition breaks down, and programming languages differ in how these values are defined.

Variants of the definition

In mathematics, the result of the modulo operation is an equivalence class, and any member of the class may be chosen as representative; however, the usual representative is the least positive residue, the smallest non-negative integer that belongs to that class (i.e., the remainder of the Euclidean division).[3] However, other conventions are possible. Computers and calculators have various ways of storing and representing numbers; thus their definition of the modulo operation depends on the programming language or the underlying hardware.

In nearly all computing systems, the quotient $q$ and the remainder $r$ of $a$ divided by $n$ satisfy the following conditions:

{\begin{aligned}q\,&\in \mathbb {Z} \\a\,&=nq+r\\|r|\,&<|n|\end{aligned}}

(1)

However, this still leaves a sign ambiguity if the remainder is nonzero: two possible choices for the remainder occur, one negative and the other positive, and two possible choices for the quotient occur. In number theory, the positive remainder is always chosen, but in computing, programming languages choose depending on the language and the signs of $a$ or $n$ .[lower-alpha 1] Standard Pascal and ALGOL 68, for example, give a positive remainder (or 0) even for negative divisors, and some programming languages, such as C90, leave it to the implementation when either of $n$ or $a$ is negative (see the table under § In programming languages for details). $a$ modulo 0 is undefined in most systems, although some do define it as $a$ .

Many implementations use truncated division, where the quotient is defined by truncation $q = trunc(.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px;white-space:nowrap} a / n)$ and thus according to equation (1) the remainder would have same sign as the dividend. The quotient is rounded towards zero: equal to the first integer in the direction of zero from the exact rational quotient.
$r=a-n\operatorname {trunc} \left({\frac {a}{n}}\right)$
Donald Knuth[4] described floored division where the quotient is defined by the floor function $q = ⌊ a / n ⌋$ and thus according to equation (1) the remainder would have the same sign as the divisor. Due to the floor function, the quotient is always rounded downwards, even if it is already negative.
$r=a-n\left\lfloor {\frac {a}{n}}\right\rfloor$
Raymond T. Boute[5] describes the Euclidean definition in which the remainder is nonnegative always, $0 \leq r$ , and is thus consistent with the Euclidean division algorithm. In this case,
$n>0\Rightarrow q=\left\lfloor {\frac {a}{n}}\right\rfloor$

$n<0\Rightarrow q=\left\lceil {\frac {a}{n}}\right\rceil$

or equivalently

$q=\operatorname {sgn}(n)\left\lfloor {\frac {a}{\left|n\right|}}\right\rfloor$

where $sgn$ is the sign function, and thus

$r=a-|n|\left\lfloor {\frac {a}{\left|n\right|}}\right\rfloor$
A round-division is where the quotient is $round(a / n)$ , i.e. rounded to the nearest integer. It is found in Common Lisp and IEEE 754 (see the round to nearest convention in IEEE-754). Thus, the sign of the remainder is chosen to be nearest to zero.
Common Lisp also defines ceiling-division (remainder different sign from divisor) where the quotient is given by $q = ⌈ a / n ⌉$ . Thus, the sign of the remainder is chosen to be different from that of the divisor.

As described by Leijen,

Boute argues that Euclidean division is superior to the other ones in terms of regularity and useful mathematical properties, although floored division, promoted by Knuth, is also a good definition. Despite its widespread use, truncated division is shown to be inferior to the other definitions.
— Daan Leijen, Division and Modulus for Computer Scientists[6]

Common pitfalls

When the result of a modulo operation has the sign of the dividend (truncating definition), it can lead to surprising mistakes.

For example, to test if an integer is odd, one might be inclined to test if the remainder by 2 is equal to 1:

bool is_odd(int n) {
    return n % 2 == 1;
}

But in a language where modulo has the sign of the dividend, that is incorrect, because when $n$ (the dividend) is negative and odd, $n$ mod 2 returns −1, and the function returns false.

One correct alternative is to test that the remainder is not 0 (because remainder 0 is the same regardless of the signs):

bool is_odd(int n) {
    return n % 2 != 0;
}

Another alternative is to use the fact that for any odd number, the remainder may be either 1 or −1:

bool is_odd(int n) {
    return n % 2 == 1 || n % 2 == -1;
}

Notation

Some calculators have a $mod()$ function button, and many programming languages have a similar function, expressed as $mod(a, n)$ , for example. Some also support expressions that use "%", "mod", or "Mod" as a modulo or remainder operator, such as a % n or a mod n.

For environments lacking a similar function, any of the three definitions above can be used.

Performance issues

Modulo operations might be implemented such that a division with a remainder is calculated each time. For special cases, on some hardware, faster alternatives exist. For example, the modulo of powers of 2 can alternatively be expressed as a bitwise AND operation (assuming $x$ is a positive integer, or using a non-truncating definition):

x % 2ⁿ == x & (2ⁿ - 1)

Examples:

x % 2 == x & 1

x % 4 == x & 3

x % 8 == x & 7

In devices and software that implement bitwise operations more efficiently than modulo, these alternative forms can result in faster calculations.[7]

Optimizing compilers may recognize expressions of the form expression % constant where constant is a power of two and automatically implement them as expression & (constant-1), allowing the programmer to write clearer code without compromising performance. This simple optimization is not possible for languages in which the result of the modulo operation has the sign of the dividend (including C), unless the dividend is of an unsigned integer type. This is because, if the dividend is negative, the modulo will be negative, whereas expression & (constant-1) will always be positive. For these languages, the equivalence x % 2ⁿ == x < 0 ? x | ~(2ⁿ - 1) : x & (2ⁿ - 1) has to be used instead, expressed using bitwise OR, NOT and AND operations.

Properties (identities)

Some modulo operations can be factored or expanded similarly to other mathematical operations. This may be useful in cryptography proofs, such as the Diffie–Hellman key exchange.

Identity:
- $(a mod n) mod n = a mod n$ .
- $n x mod n = 0$ for all positive integer values of $x$ .
- If $p$ is a prime number which is not a divisor of $b$ , then $ab p -1 mod p = a mod p$ , due to Fermat's little theorem.
Inverse:
- $[(- a mod n) + (a mod n)] mod n = 0$ .
- $b -1 mod n$ denotes the modular multiplicative inverse, which is defined if and only if $b$ and $n$ are relatively prime, which is the case when the left hand side is defined: $[(b -1 mod n)(b mod n)] mod n = 1$ .
Distributive:
- $(a + b) mod n = [(a mod n) + (b mod n)] mod n$ .
- $ab mod n = [(a mod n)(b mod n)] mod n$ .
Division (definition): $a / b mod n = [(a mod n)(b -1 mod n)] mod n$ , when the right hand side is defined (that is when $b$ and $n$ are coprime). Undefined otherwise.
Inverse multiplication: $[(ab mod n)(b -1 mod n)] mod n = a mod n$ .

In programming languages

Modulo operators in various programming languages
Language	Operator	Integer	Floating-point	Definition
ABAP	`MOD`	Yes	Yes	Euclidean
ActionScript	`%`	Yes	No	Truncated
Ada	`mod`	Yes	No	Floored
Ada	`rem`	Yes	No	Truncated
ALGOL 68	`÷×`, `mod`	Yes	No	Euclidean
AMPL	`mod`	Yes	No	Truncated
APL	[lower-alpha 2]	Yes	No	Floored
AppleScript	`mod`	Yes	No	Truncated
AutoLISP	`(rem d n)`	Yes	No	Truncated
AWK	`%`	Yes	No	Truncated
BASIC	`Mod`	Yes	No	Undefined
bc	`%`	Yes	No	Truncated
C (ISO 1990) C++ (ISO 1998)	`%`	Yes	No	Implementation-defined[8]
	`div`	Yes	No	Truncated
	`fmod` (C), `std::fmod` (C++)	No	Yes	Truncated[9]
C (ISO 1999) C++ (ISO 2011)	`%`, `div`	Yes	No	Truncated[10]
	`fmod` (C), `std::fmod` (C++)	No	Yes	Truncated
	`remainder` (C), `std::remainder` (C++)	No	Yes	Rounded
C#	`%`	Yes	Yes	Truncated
Clarion	`%`	Yes	No	Truncated
Clean	`rem`	Yes	No	Truncated
Clojure	`mod`	Yes	No	Floored
Clojure	`rem`	Yes	No	Truncated
COBOL	`FUNCTION MOD`	Yes	No	Floored[lower-alpha 3]
CoffeeScript	`%`	Yes	No	Truncated
CoffeeScript	`%%`	Yes	No	Floored[11]
ColdFusion	`%`, `MOD`	Yes	No	Truncated
Common Lisp	`mod`	Yes	Yes	Floored
Common Lisp	`rem`	Yes	Yes	Truncated
Crystal	`%`	Yes	No	Truncated
D	`%`	Yes	Yes	Truncated[12]
Dart	`%`	Yes	Yes	Euclidean
Dart	`remainder()`	Yes	Yes	Truncated
Eiffel	`\\`	Yes	No	Truncated
Elixir	`rem/2`	Yes	No	Truncated[13]
Elixir	`Integer.mod/2`	Yes	No	Floored[14]
Elm	`modBy`	Yes	No	Floored
Elm	`remainderBy`	Yes	No	Truncated
Erlang	`rem`	Yes	No	Truncated
Euphoria	`mod`	Yes	No	Floored
Euphoria	`remainder`	Yes	No	Truncated
F#	`%`	Yes	Yes	Truncated
Factor	`mod`	Yes	No	Truncated
FileMaker	`Mod`	Yes	No	Floored
Forth	`mod`	Yes	No	Implementation defined
	`fm/mod`	Yes	No	Floored
	`sm/rem`	Yes	No	Truncated
Fortran	`mod`	Yes	Yes	Truncated
Fortran	`modulo`	Yes	Yes	Floored
Frink	`mod`	Yes	No	Floored
GameMaker Studio (GML)	`mod`, `%`	Yes	No	Truncated
GDScript (Godot)	`%`	Yes	No	Truncated
	`fmod`	No	Yes	Truncated
	`posmod`	Yes	No	Floored
	`fposmod`	No	Yes	Floored
Go	`%`	Yes	No	Truncated
Go	`math.Mod`	No	Yes	Truncated
Groovy	`%`	Yes	No	Truncated
Haskell	`mod`	Yes	No	Floored
	`rem`	Yes	No	Truncated
	`Data.Fixed.mod'` (GHC)	No	Yes	Floored
Haxe	`%`	Yes	No	Truncated
J	[lower-alpha 2]	Yes	No	Floored
Java	`%`	Yes	Yes	Truncated
Java	`Math.floorMod`	Yes	No	Floored
JavaScript	`%`	Yes	Yes	Truncated
Julia	`mod`	Yes	No	Floored
Julia	`%`, `rem`	Yes	No	Truncated
Kotlin	`%`, `rem`	Yes	No	Truncated
ksh	`%`	Yes	No	Truncated (same as POSIX sh)
ksh	`fmod`	No	Yes	Truncated
LabVIEW	`mod`	Yes	Yes	Truncated
LibreOffice	`=MOD()`	Yes	No	Floored
Logo	`MODULO`	Yes	No	Floored
Logo	`REMAINDER`	Yes	No	Truncated
Lua 5	`%`	Yes	No	Floored
Lua 4	`mod(x,y)`	Yes	No	Floored
Liberty BASIC	`MOD`	Yes	No	Truncated
Mathcad	`mod(x,y)`	Yes	No	Floored
Maple	`e mod m`	Yes	No	Euclidean
Mathematica	`Mod[a, b]`	Yes	No	Floored
MATLAB	`mod`	Yes	No	Floored
MATLAB	`rem`	Yes	No	Truncated
Maxima	`mod`	Yes	No	Floored
Maxima	`remainder`	Yes	No	Truncated
Maya Embedded Language	`%`	Yes	No	Truncated
Microsoft Excel	`=MOD()`	Yes	Yes	Floored
Minitab	`MOD`	Yes	No	Floored
Modula-2	`MOD`	Yes	No	Floored
Modula-2	`REM`	Yes	No	Truncated
MUMPS	`#`	Yes	No	Floored
Netwide Assembler (NASM, NASMX)	`%`, `div` (unsigned)	Yes	No	N/A
Netwide Assembler (NASM, NASMX)	`%%` (signed)	Yes	No	Implementation-defined[15]
Nim	`mod`	Yes	No	Truncated
Oberon	`MOD`	Yes	No	Floored-like[lower-alpha 4]
Objective-C	`%`	Yes	No	Truncated (same as C99)
Object Pascal, Delphi	`mod`	Yes	No	Truncated
OCaml	`mod`	Yes	No	Truncated
OCaml	`mod_float`	No	Yes	Truncated
Occam	`\`	Yes	No	Truncated
Pascal (ISO-7185 and -10206)	`mod`	Yes	No	Euclidean-like[lower-alpha 5]
Programming Code Advanced (PCA)	`\`	Yes	No	Undefined
Perl	`%`	Yes	No	Floored[lower-alpha 6]
Perl	`POSIX::fmod`	No	Yes	Truncated
Phix	`mod`	Yes	No	Floored
Phix	`remainder`	Yes	No	Truncated
PHP	`%`	Yes	No	Truncated
PHP	`fmod`	No	Yes	Truncated
PIC BASIC Pro	`\\`	Yes	No	Truncated
PL/I	`mod`	Yes	No	Floored (ANSI PL/I)
PowerShell	`%`	Yes	No	Truncated
Programming Code (PRC)	`MATH.OP - 'MOD; (\)'`	Yes	No	Undefined
Progress	`modulo`	Yes	No	Truncated
Prolog (ISO 1995)	`mod`	Yes	No	Floored
Prolog (ISO 1995)	`rem`	Yes	No	Truncated
PureBasic	`%`, `Mod(x,y)`	Yes	No	Truncated
PureScript	`mod`	Yes	No	Floored
Python	`%`	Yes	Yes	Floored
Python	`math.fmod`	No	Yes	Truncated
Q#	`%`	Yes	No	Truncated[17]
R	`%%`	Yes	No	Floored
Racket	`modulo`	Yes	No	Floored
Racket	`remainder`	Yes	No	Truncated
Raku	`%`	No	Yes	Floored
RealBasic	`MOD`	Yes	No	Truncated
Reason	`mod`	Yes	No	Truncated
Rexx	`//`	Yes	Yes	Truncated
RPG	`%REM`	Yes	No	Truncated
Ruby	`%`, `modulo()`	Yes	Yes	Floored
Ruby	`remainder()`	Yes	Yes	Truncated
Rust	`%`	Yes	Yes	Truncated
Rust	`rem_euclid()`	Yes	Yes	Euclidean[18]
SAS	`MOD`	Yes	No	Truncated
Scala	`%`	Yes	No	Truncated
Scheme	`modulo`	Yes	No	Floored
Scheme	`remainder`	Yes	No	Truncated
Scheme R⁶RS	`mod`	Yes	No	Euclidean[19]
	`mod0`	Yes	No	Rounded[19]
	`flmod`	No	Yes	Euclidean
	`flmod0`	No	Yes	Rounded
Scratch	`mod`	Yes	No	Floored
Scratch	`mod`	No	Yes	Truncated
Seed7	`mod`	Yes	No	Floored
Seed7	`rem`	Yes	No	Truncated
SenseTalk	`modulo`	Yes	No	Floored
SenseTalk	`rem`	Yes	No	Truncated
`sh` (POSIX) (includes bash, mksh, &c.)	`%`	Yes	No	Truncated (same as C)[20]
Smalltalk	`\\`	Yes	No	Floored
Smalltalk	`rem:`	Yes	No	Truncated
Snap!	`mod`	Yes	No	Floored
Spin	`//`	Yes	No	Floored
Solidity	`%`	Yes	No	Floored
SQL (SQL:1999)	`mod(x,y)`	Yes	No	Truncated
SQL (SQL:2011)	`%`	Yes	No	Truncated
Standard ML	`mod`	Yes	No	Floored
	`Int.rem`	Yes	No	Truncated
	`Real.rem`	No	Yes	Truncated
Stata	`mod(x,y)`	Yes	No	Euclidean
Swift	`%`	Yes	No	Truncated
Swift	`truncatingRemainder(dividingBy:)`	No	Yes	Truncated
Tcl	`%`	Yes	No	Floored
TypeScript	`%`	Yes	No	Truncated
Torque	`%`	Yes	No	Truncated
Turing	`mod`	Yes	No	Floored
Verilog (2001)	`%`	Yes	No	Truncated
VHDL	`mod`	Yes	No	Floored
VHDL	`rem`	Yes	No	Truncated
VimL	`%`	Yes	No	Truncated
Visual Basic	`Mod`	Yes	No	Truncated
WebAssembly	`i32.rem_s`, `i64.rem_s`	Yes	No	Truncated
x86 assembly	`IDIV`	Yes	No	Truncated
XBase++	`%`	Yes	Yes	Truncated
XBase++	`Mod()`	Yes	Yes	Floored
Z3 theorem prover	`div`, `mod`	Yes	No	Euclidean

In addition, many computer systems provide a divmod functionality, which produces the quotient and the remainder at the same time. Examples include the x86 architecture's IDIV instruction, the C programming language's div() function, and Python's divmod() function.

Generalizations

Modulo with offset

Sometimes it is useful for the result of $a$ modulo $n$ to lie not between 0 and $n -1$ , but between some number $d$ and $d + n -1$ . In that case, $d$ is called an offset. There does not seem to be a standard notation for this operation, so let us tentatively use $a$ mod_$d$ $n$ . We thus have the following definition:[21] $x = a$ mod_$d$ $n$ just in case $d$ ≤ $x$ ≤ $d + n -1$ and $x$ mod $n = a$ mod $n$ . Clearly, the usual modulo operation corresponds to zero offset: $a$ mod $n = a$ mod₀ $n$ . The operation of modulo with offset is related to the floor function as follows:

a

mod_$d$

n

=

a-n\left\lfloor {\frac {a-d}{n}}\right\rfloor

.

(This is easy to see. Let $x=a-n\left\lfloor {\frac {a-d}{n}}\right\rfloor$ . We first show that $x$ mod $n$ = $a$ mod $n$ . It is in genereal true that ( $a$ + $b$ $n$ ) mod $n$ = $a$ mod $n$ for all integers $b$ ; thus, this is true also in the particular case when $b$ = $-\left\lfloor {\frac {a-d}{n}}\right\rfloor$ ; but that means that $x\;{\text{mod}}\;n=\left(a-n\left\lfloor {\frac {a-d}{n}}\right\rfloor \right)\;{\text{mod}}\;n=a\;{\text{mod}}\;n$ , which is what we wanted to prove. It remains to be shown that $d$ ≤ $x$ ≤ $d + n -1$ . Let $k$ and $r$ be the integers such that $a - d = kn + r$ with 0 ≤ $r$ ≤ $n -1$ (see Euclidean division). Then $\left\lfloor {\frac {a-d}{n}}\right\rfloor =k$ , thus $x=a-n\left\lfloor {\frac {a-d}{n}}\right\rfloor =a-nk=d+r$ . Now take 0 ≤ $r$ ≤ $n -1$ and add $d$ to both sides, obtaining $d$ ≤ $d + r$ ≤ $d + n -1$ . But we've seen that $x = d + r$ , so we are done. □)

The modulo with offset $a$ mod_$d$ $n$ is implemented in Mathematica as[21] Mod[a, n, d].

Implementing other modulo definitions using truncation

Despite the mathematic elegance of Kunth's floored division and Euclidean division, it is generally much more common to find a truncated division-based modulo in programming languages. Leijen provides the following algorithms for calculating the two divisions given a truncated integer division:[6]

/* Euclidean and Floored divmod, in the style of C's ldiv() */
typedef struct {
  /* This structure is part of the C stdlib.h, but is reproduced here for clarity */
  long int quot;
  long int rem;
} ldiv_t;

/* Euclidean division */
inline ldiv_t ldivE(long numer, long denom) {
  /* The C99 and C++11 languages define both of these as truncating. */
  long q = numer / denom;
  long r = numer % denom;
  if (r < 0) {
    if (denom > 0) {
      q = q - 1;
      r = r + denom;
    } else {
      q = q + 1;
      r = r - denom;
    }
  }
  return (ldiv_t){.quot = q, .rem = r};
}

/* Floored division */
inline ldiv_t ldivF(long numer, long denom) {
  long q = numer / denom;
  long r = numer % denom;
  if ((r > 0 && denom < 0) || (r < 0 && denom > 0)) {
    q = q - 1;
    r = r + denom;
  }
  return (ldiv_t){.quot = q, .rem = r};
}

Note that for both cases, the remainder can be calculated independently of the quotient, but not vice versa. The operations are combined here to save screen space, as the logical branches are the same.

Notes

Mathematically, these two choices are but two of the infinite number of choices available for the inequality satisfied by a remainder.
Argument order reverses, i.e., α|ω computes $\omega {\bmod {\alpha }}$ , the remainder when dividing ω by α.
As implemented in ACUCOBOL, Micro Focus COBOL, and possible others.
Divisor must be positive, otherwise undefined.
As discussed by Boute, ISO Pascal's definitions of div and mod do not obey the Division Identity, and are thus fundamentally broken.
Perl usually uses arithmetic modulo operator that is machine-independent. For examples and exceptions, see the Perl documentation on multiplicative operators.[16]

References

"The Definitive Glossary of Higher Mathematical Jargon: Modulo". Math Vault. 2019-08-01. Retrieved 2020-08-27.
Weisstein, Eric W. "Congruence". mathworld.wolfram.com. Retrieved 2020-08-27.
Caldwell, Chris. "residue". Prime Glossary. Retrieved August 27, 2020.
Knuth, Donald. E. (1972). The Art of Computer Programming. Addison-Wesley.
Boute, Raymond T. (April 1992). "The Euclidean definition of the functions div and mod". ACM Transactions on Programming Languages and Systems. ACM Press (New York, NY, USA). 14 (2): 127–144. doi:10.1145/128861.128862. hdl:1854/LU-314490.
Leijen, Daan (December 3, 2001). "Division and Modulus for Computer Scientists" (PDF). Retrieved 2014-12-25.
Horvath, Adam (July 5, 2012). "Faster division and modulo operation - the power of two".
"ISO/IEC 14882:2003: Programming languages – C++". International Organization for Standardization (ISO), International Electrotechnical Commission (IEC). 2003. sec. 5.6.4. the binary % operator yields the remainder from the division of the first expression by the second. .... If both operands are nonnegative then the remainder is nonnegative; if not, the sign of the remainder is implementation-defined Cite journal requires |journal= (help)
"ISO/IEC 9899:1990: Programming languages – C". ISO, IEC. 1990. sec. 7.5.6.4. The fmod function returns the value x - i * y, for some integer i such that, if y is nonzero, the result as the same sign as x and magnitude less than the magnitude of y. Cite journal requires |journal= (help)
"C99 specification (ISO/IEC 9899:TC2)" (PDF). 2005-05-06. sec. 6.5.5 Multiplicative operators. Retrieved 16 August 2018.
CoffeeScript operators
"Expressions". D Programming Language 2.0. Digital Mars. Retrieved 29 July 2010.
"Kernel — Elixir v1.11.3". hexdocs.pm. Retrieved 2021-01-28.
"Integer — Elixir v1.11.3". hexdocs.pm. Retrieved 2021-01-28.
"Chapter 3: The NASM Language". NASM - The Netwide Assembler version 2.15.05.
Perl documentation
QuantumWriter. "Expressions". docs.microsoft.com. Retrieved 2018-07-11.
r6rs.org
"Shell Command Language". pubs.opengroup.org. Retrieved 2021-02-05.
"Mod". Wolfram Language & System Documentation Center. Wolfram Research. 2020. Retrieved April 8, 2020.

External links

Modulorama, animation of a cyclic representation of multiplication tables (explanation in French)

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

[4] Mathematically, these two choices are but two of the infinite number of choices available for the inequality satisfied by a remainder.

[rev-9] Argument order reverses, i.e., α|ω computes $\omega {\bmod {\alpha }}$ , the remainder when dividing ω by α.

[13] As implemented in ACUCOBOL, Micro Focus COBOL, and possible others.

[19] Divisor must be positive, otherwise undefined.

[20] As discussed by Boute, ISO Pascal's definitions of div and mod do not obey the Division Identity, and are thus fundamentally broken.

[22] Perl usually uses arithmetic modulo operator that is machine-independent. For examples and exceptions, see the Perl documentation on multiplicative operators.[16]

[1] "The Definitive Glossary of Higher Mathematical Jargon: Modulo". Math Vault. 2019-08-01. Retrieved 2020-08-27.

[2] Weisstein, Eric W. "Congruence". mathworld.wolfram.com. Retrieved 2020-08-27.

[3] Caldwell, Chris. "residue". Prime Glossary. Retrieved August 27, 2020.

[5] Knuth, Donald. E. (1972). The Art of Computer Programming. Addison-Wesley.

[6] Boute, Raymond T. (April 1992). "The Euclidean definition of the functions div and mod". ACM Transactions on Programming Languages and Systems. ACM Press (New York, NY, USA). 14 (2): 127–144. doi:10.1145/128861.128862. hdl:1854/LU-314490.

[Leijen-7] Leijen, Daan (December 3, 2001). "Division and Modulus for Computer Scientists" (PDF). Retrieved 2014-12-25.

[8] Horvath, Adam (July 5, 2012). "Faster division and modulo operation - the power of two".

[10] "ISO/IEC 14882:2003: Programming languages – C++". International Organization for Standardization (ISO), International Electrotechnical Commission (IEC). 2003. sec. 5.6.4. the binary % operator yields the remainder from the division of the first expression by the second. .... If both operands are nonnegative then the remainder is nonnegative; if not, the sign of the remainder is implementation-defined Cite journal requires |journal= (help)

[11] "ISO/IEC 9899:1990: Programming languages – C". ISO, IEC. 1990. sec. 7.5.6.4. The fmod function returns the value x - i * y, for some integer i such that, if y is nonzero, the result as the same sign as x and magnitude less than the magnitude of y. Cite journal requires |journal= (help)

[C99-12] "C99 specification (ISO/IEC 9899:TC2)" (PDF). 2005-05-06. sec. 6.5.5 Multiplicative operators. Retrieved 16 August 2018.

[CoffeeScript-14] CoffeeScript operators

[15] "Expressions". D Programming Language 2.0. Digital Mars. Retrieved 29 July 2010.

[16] "Kernel — Elixir v1.11.3". hexdocs.pm. Retrieved 2021-01-28.

[17] "Integer — Elixir v1.11.3". hexdocs.pm. Retrieved 2021-01-28.

[18] "Chapter 3: The NASM Language". NASM - The Netwide Assembler version 2.15.05.

[21] Perl documentation

[23] QuantumWriter. "Expressions". docs.microsoft.com. Retrieved 2018-07-11.

[r6rs-25] r6rs.org

[26] "Shell Command Language". pubs.opengroup.org. Retrieved 2021-02-05.

[Mathematica_Mod-27] "Mod". Wolfram Language & System Documentation Center. Wolfram Research. 2020. Retrieved April 8, 2020.