Mathematics

Mathematical Operators

Base.:- — Method

-(x)

Unary minus operator.

See also: abs, flipsign.

Examples

julia> -1
-1
julia> -(2)
-2
julia> -[1 2; 3 4]
2×2 Matrix{Int64}:
 -1  -2
 -3  -4

source

Base.:+ — Function

+(x, y...)

Addition operator. x+y+z+... calls this function with all arguments, i.e. +(x, y, z, ...).

Examples

julia> 1 + 20 + 4
25
julia> +(1, 20, 4)
25

source

dt::Date + t::Time -> DateTime

The addition of a Date with a Time produces a DateTime. The hour, minute, second, and millisecond parts of the Time are used along with the year, month, and day of the Date to create the new DateTime. Non-zero microseconds or nanoseconds in the Time type will result in an InexactError being thrown.

Base.:- — Method

-(x, y)

Subtraction operator.

Examples

julia> 2 - 3
-1
julia> -(2, 4.5)
-2.5

source

Base.:* — Method

*(x, y...)

Multiplication operator. x*y*z*... calls this function with all arguments, i.e. *(x, y, z, ...).

Examples

julia> 2 * 7 * 8
112
julia> *(2, 7, 8)
112

source

Base.:/ — Function

/(x, y)

Right division operator: multiplication of x by the inverse of y on the right. Gives floating-point results for integer arguments.

Examples

julia> 1/2
0.5
julia> 4/2
2.0
julia> 4.5/2
2.25

source

A / B

Matrix right-division: A / B is equivalent to (B' \ A')' where \ is the left-division operator. For square matrices, the result X is such that A == X*B.

See also: rdiv!.

Examples

julia> A = Float64[1 4 5; 3 9 2]; B = Float64[1 4 2; 3 4 2; 8 7 1];
julia> X = A / B
2×3 Matrix{Float64}:
 -0.65   3.75  -1.2
  3.25  -2.75   1.0
julia> isapprox(A, X*B)
true
julia> isapprox(X, A*pinv(B))
true

Base.:\ — Method

\(x, y)

Left division operator: multiplication of y by the inverse of x on the left. Gives floating-point results for integer arguments.

Examples

julia> 3 \ 6
2.0
julia> inv(3) * 6
2.0
julia> A = [4 3; 2 1]; x = [5, 6];
julia> A \ x
2-element Vector{Float64}:
  6.5
 -7.0
julia> inv(A) * x
2-element Vector{Float64}:
  6.5
 -7.0

source

Base.:^ — Method

^(x, y)

Exponentiation operator. If x is a matrix, computes matrix exponentiation.

If y is an Int literal (e.g. 2 in x^2 or -3 in x^-3), the Julia code x^y is transformed by the compiler to Base.literal_pow(^, x, Val(y)), to enable compile-time specialization on the value of the exponent. (As a default fallback we have Base.literal_pow(^, x, Val(y)) = ^(x,y), where usually ^ == Base.^ unless ^ has been defined in the calling namespace.) If y is a negative integer literal, then Base.literal_pow transforms the operation to inv(x)^-y by default, where -y is positive.

Examples

julia> 3^5
243
julia> A = [1 2; 3 4]
2×2 Matrix{Int64}:
 1  2
 3  4
julia> A^3
2×2 Matrix{Int64}:
 37   54
 81  118

source

Base.fma — Function

fma(x, y, z)

Computes x*y+z without rounding the intermediate result x*y. On some systems this is significantly more expensive than x*y+z. fma is used to improve accuracy in certain algorithms. See muladd.

source

Base.muladd — Function

muladd(A, y, z)

Combined multiply-add, A*y .+ z, for matrix-matrix or matrix-vector multiplication. The result is always the same size as A*y, but z may be smaller, or a scalar.

Julia 1.6

These methods require Julia 1.6 or later.

Examples

julia> A=[1.0 2.0; 3.0 4.0]; B=[1.0 1.0; 1.0 1.0]; z=[0, 100];
julia> muladd(A, B, z)
2×2 Matrix{Float64}:
   3.0    3.0
 107.0  107.0

muladd(x, y, z)

Combined multiply-add: computes x*y+z, but allowing the add and multiply to be merged with each other or with surrounding operations for performance. For example, this may be implemented as an fma if the hardware supports it efficiently. The result can be different on different machines and can also be different on the same machine due to constant propagation or other optimizations. See fma.

Examples

julia> muladd(3, 2, 1)
7
julia> 3 * 2 + 1
7

source

Base.inv — Method

inv(x)

Return the multiplicative inverse of x, such that x*inv(x) or inv(x)*x yields one(x) (the multiplicative identity) up to roundoff errors.

If x is a number, this is essentially the same as one(x)/x, but for some types inv(x) may be slightly more efficient.

Examples

julia> inv(2)
0.5
julia> inv(1 + 2im)
0.2 - 0.4im
julia> inv(1 + 2im) * (1 + 2im)
1.0 + 0.0im
julia> inv(2//3)
3//2

Julia 1.2

inv(::Missing) requires at least Julia 1.2.

source

Base.div — Function

div(x, y)
÷(x, y)

The quotient from Euclidean (integer) division. Generally equivalent to a mathematical operation x/y without a fractional part.

See also: cld, fld, rem, divrem.

Examples

julia> 9 ÷ 4
2
julia> -5 ÷ 3
-1
julia> 5.0 ÷ 2
2.0
julia> div.(-5:5, 3)'
1×11 adjoint(::Vector{Int64}) with eltype Int64:
 -1  -1  -1  0  0  0  0  0  1  1  1

source

Base.fld — Function

fld(x, y)

Largest integer less than or equal to x/y. Equivalent to div(x, y, RoundDown).

See also div, cld, fld1.

Examples

julia> fld(7.3,5.5)
1.0
julia> fld.(-5:5, 3)'
1×11 adjoint(::Vector{Int64}) with eltype Int64:
 -2  -2  -1  -1  -1  0  0  0  1  1  1

Because fld(x, y) implements strictly correct floored rounding based on the true value of floating-point numbers, unintuitive situations can arise. For example:

julia> fld(6.0,0.1)
59.0
julia> 6.0/0.1
60.0
julia> 6.0/big(0.1)
59.99999999999999666933092612453056361837965690217069245739573412231113406246995

What is happening here is that the true value of the floating-point number written as 0.1 is slightly larger than the numerical value 1/10 while 6.0 represents the number 6 precisely. Therefore the true value of 6.0 / 0.1 is slightly less than 60. When doing division, this is rounded to precisely 60.0, but fld(6.0, 0.1) always takes the floor of the true value, so the result is 59.0.

source

Base.cld — Function

cld(x, y)

Smallest integer larger than or equal to x/y. Equivalent to div(x, y, RoundUp).

See also div, fld.

Examples

julia> cld(5.5,2.2)
3.0
julia> cld.(-5:5, 3)'
1×11 adjoint(::Vector{Int64}) with eltype Int64:
 -1  -1  -1  0  0  0  1  1  1  2  2

source

Base.mod — Function

mod(x::Integer, r::AbstractUnitRange)

Find y in the range r such that $x ≡ y (mod n)$, where n = length(r), i.e. y = mod(x - first(r), n) + first(r).

See also mod1.

Examples

julia> mod(0, Base.OneTo(3))  # mod1(0, 3)
3
julia> mod(3, 0:2)  # mod(3, 3)
0

Julia 1.3

This method requires at least Julia 1.3.

source

mod(x, y)
rem(x, y, RoundDown)

The reduction of x modulo y, or equivalently, the remainder of x after floored division by y, i.e. x - y*fld(x,y) if computed without intermediate rounding.

The result will have the same sign as y, and magnitude less than abs(y) (with some exceptions, see note below).

Note

When used with floating point values, the exact result may not be representable by the type, and so rounding error may occur. In particular, if the exact result is very close to y, then it may be rounded to y.

See also: rem, div, fld, mod1, invmod.

julia> mod(8, 3)
2
julia> mod(9, 3)
0
julia> mod(8.9, 3)
2.9000000000000004
julia> mod(eps(), 3)
2.220446049250313e-16
julia> mod(-eps(), 3)
3.0
julia> mod.(-5:5, 3)'
1×11 adjoint(::Vector{Int64}) with eltype Int64:
 1  2  0  1  2  0  1  2  0  1  2

source

rem(x::Integer, T::Type{<:Integer}) -> T
mod(x::Integer, T::Type{<:Integer}) -> T
%(x::Integer, T::Type{<:Integer}) -> T

Find y::T such that x ≡ y (mod n), where n is the number of integers representable in T, and y is an integer in [typemin(T),typemax(T)]. If T can represent any integer (e.g. T == BigInt), then this operation corresponds to a conversion to T.

Examples

julia> 129 % Int8
-127

source

Base.rem — Function

rem(x, y)
%(x, y)

Remainder from Euclidean division, returning a value of the same sign as x, and smaller in magnitude than y. This value is always exact.

See also: div, mod, mod1, divrem.

Examples

julia> x = 15; y = 4;
julia> x % y
3
julia> x == div(x, y) * y + rem(x, y)
true
julia> rem.(-5:5, 3)'
1×11 adjoint(::Vector{Int64}) with eltype Int64:
 -2  -1  0  -2  -1  0  1  2  0  1  2

source

Base.Math.rem2pi — Function

rem2pi(x, r::RoundingMode)

Compute the remainder of x after integer division by 2π, with the quotient rounded according to the rounding mode r. In other words, the quantity

x - 2π*round(x/(2π),r)

without any intermediate rounding. This internally uses a high precision approximation of 2π, and so will give a more accurate result than rem(x,2π,r)

• if r == RoundNearest, then the result is in the interval $[-π, π]$. This will generally be the most accurate result. See also RoundNearest.

• if r == RoundToZero, then the result is in the interval $[0, 2π]$ if x is positive,. or $[-2π, 0]$ otherwise. See also RoundToZero.

• if r == RoundDown, then the result is in the interval $[0, 2π]$. See also RoundDown.

• if r == RoundUp, then the result is in the interval $[-2π, 0]$. See also RoundUp.

Examples

julia> rem2pi(7pi/4, RoundNearest)
-0.7853981633974485
julia> rem2pi(7pi/4, RoundDown)
5.497787143782138

source

Base.Math.mod2pi — Function

mod2pi(x)

Modulus after division by 2π, returning in the range $[0,2π)$.

This function computes a floating point representation of the modulus after division by numerically exact 2π, and is therefore not exactly the same as mod(x,2π), which would compute the modulus of x relative to division by the floating-point number 2π.

Note

Depending on the format of the input value, the closest representable value to 2π may be less than 2π. For example, the expression mod2pi(2π) will not return 0, because the intermediate value of 2*π is a Float64 and 2*Float64(π) < 2*big(π). See rem2pi for more refined control of this behavior.

Examples

julia> mod2pi(9*pi/4)
0.7853981633974481

source

Base.divrem — Function

divrem(x, y, r::RoundingMode=RoundToZero)

The quotient and remainder from Euclidean division. Equivalent to (div(x,y,r), rem(x,y,r)). Equivalently, with the default value of r, this call is equivalent to (x÷y, x%y).

See also: fldmod, cld.

Examples

julia> divrem(3,7)
(0, 3)
julia> divrem(7,3)
(2, 1)

source

Base.fldmod — Function

fldmod(x, y)

The floored quotient and modulus after division. A convenience wrapper for divrem(x, y, RoundDown). Equivalent to (fld(x,y), mod(x,y)).

See also: fld, cld, fldmod1.

source

Base.fld1 — Function

fld1(x, y)

Flooring division, returning a value consistent with mod1(x,y)

See also mod1, fldmod1.

Examples

julia> x = 15; y = 4;
julia> fld1(x, y)
4
julia> x == fld(x, y) * y + mod(x, y)
true
julia> x == (fld1(x, y) - 1) * y + mod1(x, y)
true

source

Base.mod1 — Function

mod1(x, y)

Modulus after flooring division, returning a value r such that mod(r, y) == mod(x, y) in the range $(0, y]$ for positive y and in the range $[y,0)$ for negative y.

With integer arguments and positive y, this is equal to mod(x, 1:y), and hence natural for 1-based indexing. By comparison, mod(x, y) == mod(x, 0:y-1) is natural for computations with offsets or strides.

See also mod, fld1, fldmod1.

Examples

julia> mod1(4, 2)
2
julia> mod1.(-5:5, 3)'
1×11 adjoint(::Vector{Int64}) with eltype Int64:
 1  2  3  1  2  3  1  2  3  1  2
julia> mod1.([-0.1, 0, 0.1, 1, 2, 2.9, 3, 3.1]', 3)
1×8 Matrix{Float64}:
 2.9  3.0  0.1  1.0  2.0  2.9  3.0  0.1

source

Base.fldmod1 — Function

fldmod1(x, y)

Return (fld1(x,y), mod1(x,y)).

See also fld1, mod1.

source

Base.:// — Function

//(num, den)

Divide two integers or rational numbers, giving a Rational result.

Examples

julia> 3 // 5
3//5
julia> (3 // 5) // (2 // 1)
3//10

source

Base.rationalize — Function

rationalize([T<:Integer=Int,] x; tol::Real=eps(x))

Approximate floating point number x as a Rational number with components of the given integer type. The result will differ from x by no more than tol.

Examples

julia> rationalize(5.6)
28//5
julia> a = rationalize(BigInt, 10.3)
103//10
julia> typeof(numerator(a))
BigInt

source

Base.numerator — Function

numerator(x)

Numerator of the rational representation of x.

Examples

julia> numerator(2//3)
2
julia> numerator(4)
4

source

Base.denominator — Function

denominator(x)

Denominator of the rational representation of x.

Examples

julia> denominator(2//3)
3
julia> denominator(4)
1

source

Base.:<< — Function

<<(x, n)

Left bit shift operator, x << n. For n >= 0, the result is x shifted left by n bits, filling with 0s. This is equivalent to x * 2^n. For n < 0, this is equivalent to x >> -n.

Examples

julia> Int8(3) << 2
12
julia> bitstring(Int8(3))
"00000011"
julia> bitstring(Int8(12))
"00001100"

See also >>, >>>, exp2, ldexp.

source

<<(B::BitVector, n) -> BitVector

Left bit shift operator, B << n. For n >= 0, the result is B with elements shifted n positions backwards, filling with false values. If n < 0, elements are shifted forwards. Equivalent to B >> -n.

Examples

julia> B = BitVector([true, false, true, false, false])
5-element BitVector:
 1
 0
 1
 0
 0
julia> B << 1
5-element BitVector:
 0
 1
 0
 0
 0
julia> B << -1
5-element BitVector:
 0
 1
 0
 1
 0

source

Base.:>> — Function

>>(x, n)

Right bit shift operator, x >> n. For n >= 0, the result is x shifted right by n bits, where n >= 0, filling with 0s if x >= 0, 1s if x < 0, preserving the sign of x. This is equivalent to fld(x, 2^n). For n < 0, this is equivalent to x << -n.

Examples

julia> Int8(13) >> 2
3
julia> bitstring(Int8(13))
"00001101"
julia> bitstring(Int8(3))
"00000011"
julia> Int8(-14) >> 2
-4
julia> bitstring(Int8(-14))
"11110010"
julia> bitstring(Int8(-4))
"11111100"

See also >>>, <<.

source

>>(B::BitVector, n) -> BitVector

Right bit shift operator, B >> n. For n >= 0, the result is B with elements shifted n positions forward, filling with false values. If n < 0, elements are shifted backwards. Equivalent to B << -n.

Examples

julia> B = BitVector([true, false, true, false, false])
5-element BitVector:
 1
 0
 1
 0
 0
julia> B >> 1
5-element BitVector:
 0
 1
 0
 1
 0
julia> B >> -1
5-element BitVector:
 0
 1
 0
 0
 0

source

Base.:>>> — Function

>>>(x, n)

Unsigned right bit shift operator, x >>> n. For n >= 0, the result is x shifted right by n bits, where n >= 0, filling with 0s. For n < 0, this is equivalent to x << -n.

For Unsigned integer types, this is equivalent to >>. For Signed integer types, this is equivalent to signed(unsigned(x) >> n).

Examples

julia> Int8(-14) >>> 2
60
julia> bitstring(Int8(-14))
"11110010"
julia> bitstring(Int8(60))
"00111100"

BigInts are treated as if having infinite size, so no filling is required and this is equivalent to >>.

See also >>, <<.

source

>>>(B::BitVector, n) -> BitVector

Unsigned right bitshift operator, B >>> n. Equivalent to B >> n. See >> for details and examples.

source

Base.bitrotate — Function

bitrotate(x::Base.BitInteger, k::Integer)

bitrotate(x, k) implements bitwise rotation. It returns the value of x with its bits rotated left k times. A negative value of k will rotate to the right instead.

Julia 1.5

This function requires Julia 1.5 or later.

See also: <<, circshift, BitArray.

julia> bitrotate(UInt8(114), 2)
0xc9
julia> bitstring(bitrotate(0b01110010, 2))
"11001001"
julia> bitstring(bitrotate(0b01110010, -2))
"10011100"
julia> bitstring(bitrotate(0b01110010, 8))
"01110010"

source

Base.:: — Function

(:)(start::CartesianIndex, [step::CartesianIndex], stop::CartesianIndex)

Construct CartesianIndices from two CartesianIndex and an optional step.

Julia 1.1

This method requires at least Julia 1.1.

Julia 1.6

The step range method start:step:stop requires at least Julia 1.6.

Examples

julia> I = CartesianIndex(2,1);
julia> J = CartesianIndex(3,3);
julia> I:J
CartesianIndices((2:3, 1:3))
julia> I:CartesianIndex(1, 2):J
CartesianIndices((2:1:3, 1:2:3))

source

(:)(start, [step], stop)

Range operator. a:b constructs a range from a to b with a step size of 1 (a UnitRange) , and a:s:b is similar but uses a step size of s (a StepRange).

: is also used in indexing to select whole dimensions and for Symbol literals, as in e.g. :hello.

source

Base.range — Function

range(start, stop, length)
range(start, stop; length, step)
range(start; length, stop, step)
range(;start, length, stop, step)

Construct a specialized array with evenly spaced elements and optimized storage (an AbstractRange) from the arguments. Mathematically a range is uniquely determined by any three of start, step, stop and length. Valid invocations of range are:

• Call range with any three of start, step, stop, length.
• Call range with two of start, stop, length. In this case step will be assumed to be one. If both arguments are Integers, a UnitRange will be returned.
• Call range with one of stop or length. start and step will be assumed to be one.

See Extended Help for additional details on the returned type.

Examples

julia> range(1, length=100)
1:100
julia> range(1, stop=100)
1:100
julia> range(1, step=5, length=100)
1:5:496
julia> range(1, step=5, stop=100)
1:5:96
julia> range(1, 10, length=101)
1.0:0.09:10.0
julia> range(1, 100, step=5)
1:5:96
julia> range(stop=10, length=5)
6:10
julia> range(stop=10, step=1, length=5)
6:1:10
julia> range(start=1, step=1, stop=10)
1:1:10
julia> range(; length = 10)
Base.OneTo(10)
julia> range(; stop = 6)
Base.OneTo(6)
julia> range(; stop = 6.5)
1.0:1.0:6.0

If length is not specified and stop - start is not an integer multiple of step, a range that ends before stop will be produced.

julia> range(1, 3.5, step=2)
1.0:2.0:3.0

Special care is taken to ensure intermediate values are computed rationally. To avoid this induced overhead, see the LinRange constructor.

Julia 1.1

stop as a positional argument requires at least Julia 1.1.

Julia 1.7

The versions without keyword arguments and start as a keyword argument require at least Julia 1.7.

Julia 1.8

The versions with stop as a sole keyword argument, or length as a sole keyword argument require at least Julia 1.8.

Extended Help

range will produce a Base.OneTo when the arguments are Integers and

• Only length is provided
• Only stop is provided

range will produce a UnitRange when the arguments are Integers and

• Only start and stop are provided
• Only length and stop are provided

A UnitRange is not produced if step is provided even if specified as one.

source

Base.OneTo — Type

Base.OneTo(n)

Define an AbstractUnitRange that behaves like 1:n, with the added distinction that the lower limit is guaranteed (by the type system) to be 1.

source

Base.StepRangeLen — Type

StepRangeLen(         ref::R, step::S, len, [offset=1]) where {  R,S}
StepRangeLen{T,R,S}(  ref::R, step::S, len, [offset=1]) where {T,R,S}
StepRangeLen{T,R,S,L}(ref::R, step::S, len, [offset=1]) where {T,R,S,L}

A range r where r[i] produces values of type T (in the first form, T is deduced automatically), parameterized by a reference value, a step, and the length. By default ref is the starting value r[1], but alternatively you can supply it as the value of r[offset] for some other index 1 <= offset <= len. In conjunction with TwicePrecision this can be used to implement ranges that are free of roundoff error.

source

Base.:== — Function

==(x, y)

Generic equality operator. Falls back to \===. Should be implemented for all types with a notion of equality, based on the abstract value that an instance represents. For example, all numeric types are compared by numeric value, ignoring type. Strings are compared as sequences of characters, ignoring encoding. For collections, == is generally called recursively on all contents, though other properties (like the shape for arrays) may also be taken into account.

This operator follows IEEE semantics for floating-point numbers: 0.0 == -0.0 and NaN != NaN.

The result is of type Bool, except when one of the operands is missing, in which case missing is returned (three-valued logic). For collections, missing is returned if at least one of the operands contains a missing value and all non-missing values are equal. Use isequal or \=== to always get a Bool result.

Implementation

New numeric types should implement this function for two arguments of the new type, and handle comparison to other types via promotion rules where possible.

isequal falls back to ==, so new methods of == will be used by the Dict type to compare keys. If your type will be used as a dictionary key, it should therefore also implement hash.

If some type defines ==, isequal, and isless then it should also implement < to ensure consistency of comparisons.

source

Base.:!= — Function

!=(x, y)
≠(x,y)

Not-equals comparison operator. Always gives the opposite answer as \==.

Implementation

New types should generally not implement this, and rely on the fallback definition !=(x,y) = !(x==y) instead.

Examples

julia> 3 != 2
true
julia> "foo" ≠ "foo"
false

source

!=(x)

Create a function that compares its argument to x using !=, i.e. a function equivalent to y -> y != x. The returned function is of type Base.Fix2{typeof(!=)}, which can be used to implement specialized methods.

Julia 1.2

This functionality requires at least Julia 1.2.

source

Base.:!== — Function

!==(x, y)
≢(x,y)

Always gives the opposite answer as \===.

Examples

julia> a = [1, 2]; b = [1, 2];
julia> a ≢ b
true
julia> a ≢ a
false

source

Base.:< — Function

<(x, y)

Less-than comparison operator. Falls back to isless. Because of the behavior of floating-point NaN values, this operator implements a partial order.

Implementation

New numeric types with a canonical partial order should implement this function for two arguments of the new type. Types with a canonical total order should implement isless instead.

Examples

julia> 'a' < 'b'
true
julia> "abc" < "abd"
true
julia> 5 < 3
false

source

<(x)

Create a function that compares its argument to x using <, i.e. a function equivalent to y -> y < x. The returned function is of type Base.Fix2{typeof(<)}, which can be used to implement specialized methods.

Julia 1.2

This functionality requires at least Julia 1.2.

source

Base.:<= — Function

<=(x, y)
≤(x,y)

Less-than-or-equals comparison operator. Falls back to (x < y) | (x == y).

Examples

julia> 'a' <= 'b'
true
julia> 7 ≤ 7 ≤ 9
true
julia> "abc" ≤ "abc"
true
julia> 5 <= 3
false

source

<=(x)

Create a function that compares its argument to x using <=, i.e. a function equivalent to y -> y <= x. The returned function is of type Base.Fix2{typeof(<=)}, which can be used to implement specialized methods.

Julia 1.2

This functionality requires at least Julia 1.2.

source

Base.:> — Function

>(x, y)

Greater-than comparison operator. Falls back to y < x.

Implementation

Generally, new types should implement < instead of this function, and rely on the fallback definition >(x, y) = y < x.

Examples

julia> 'a' > 'b'
false
julia> 7 > 3 > 1
true
julia> "abc" > "abd"
false
julia> 5 > 3
true

source

>(x)

Create a function that compares its argument to x using >, i.e. a function equivalent to y -> y > x. The returned function is of type Base.Fix2{typeof(>)}, which can be used to implement specialized methods.

Julia 1.2

This functionality requires at least Julia 1.2.

source

Base.:>= — Function

>=(x, y)
≥(x,y)

Greater-than-or-equals comparison operator. Falls back to y <= x.

Examples

julia> 'a' >= 'b'
false
julia> 7 ≥ 7 ≥ 3
true
julia> "abc" ≥ "abc"
true
julia> 5 >= 3
true

source

>=(x)

Create a function that compares its argument to x using >=, i.e. a function equivalent to y -> y >= x. The returned function is of type Base.Fix2{typeof(>=)}, which can be used to implement specialized methods.

Julia 1.2

This functionality requires at least Julia 1.2.

source

Base.cmp — Function

cmp(x,y)

Return -1, 0, or 1 depending on whether x is less than, equal to, or greater than y, respectively. Uses the total order implemented by isless.

Examples

julia> cmp(1, 2)
-1
julia> cmp(2, 1)
1
julia> cmp(2+im, 3-im)
ERROR: MethodError: no method matching isless(::Complex{Int64}, ::Complex{Int64})
[...]

source

cmp(<, x, y)

Return -1, 0, or 1 depending on whether x is less than, equal to, or greater than y, respectively. The first argument specifies a less-than comparison function to use.

source

cmp(a::AbstractString, b::AbstractString) -> Int

Compare two strings. Return 0 if both strings have the same length and the character at each index is the same in both strings. Return -1 if a is a prefix of b, or if a comes before b in alphabetical order. Return 1 if b is a prefix of a, or if b comes before a in alphabetical order (technically, lexicographical order by Unicode code points).

Examples

julia> cmp("abc", "abc")
0
julia> cmp("ab", "abc")
-1
julia> cmp("abc", "ab")
1
julia> cmp("ab", "ac")
-1
julia> cmp("ac", "ab")
1
julia> cmp("α", "a")
1
julia> cmp("b", "β")
-1

source

Base.:~ — Function

~(x)

Bitwise not.

See also: !, &, |.

Examples

julia> ~4
-5
julia> ~10
-11
julia> ~true
false

source

Base.:& — Function

x & y

Bitwise and. Implements three-valued logic, returning missing if one operand is missing and the other is true. Add parentheses for function application form: (&)(x, y).

See also: |, xor, &&.

Examples

julia> 4 & 10
0
julia> 4 & 12
4
julia> true & missing
missing
julia> false & missing
false

source

Base.:| — Function

x | y

Bitwise or. Implements three-valued logic, returning missing if one operand is missing and the other is false.

See also: &, xor, ||.

Examples

julia> 4 | 10
14
julia> 4 | 1
5
julia> true | missing
true
julia> false | missing
missing

source

Base.xor — Function

xor(x, y)
⊻(x, y)

Bitwise exclusive or of x and y. Implements three-valued logic, returning missing if one of the arguments is missing.

The infix operation a ⊻ b is a synonym for xor(a,b), and ⊻ can be typed by tab-completing \xor or \veebar in the Julia REPL.

Examples

julia> xor(true, false)
true
julia> xor(true, true)
false
julia> xor(true, missing)
missing
julia> false ⊻ false
false
julia> [true; true; false] .⊻ [true; false; false]
3-element BitVector:
 0
 1
 0

source

Base.nand — Function

nand(x, y)
⊼(x, y)

Bitwise nand (not and) of x and y. Implements three-valued logic, returning missing if one of the arguments is missing.

The infix operation a ⊼ b is a synonym for nand(a,b), and ⊼ can be typed by tab-completing \nand or \barwedge in the Julia REPL.

Examples

julia> nand(true, false)
true
julia> nand(true, true)
false
julia> nand(true, missing)
missing
julia> false ⊼ false
true
julia> [true; true; false] .⊼ [true; false; false]
3-element BitVector:
 0
 1
 1

source

Base.nor — Function

nor(x, y)
⊽(x, y)

Bitwise nor (not or) of x and y. Implements three-valued logic, returning missing if one of the arguments is missing.

The infix operation a ⊽ b is a synonym for nor(a,b), and ⊽ can be typed by tab-completing \nor or \barvee in the Julia REPL.

Examples

julia> nor(true, false)
false
julia> nor(true, true)
false
julia> nor(true, missing)
false
julia> false ⊽ false
true
julia> [true; true; false] .⊽ [true; false; false]
3-element BitVector:
 0
 0
 1

source

Base.:! — Function

!(x)

Boolean not. Implements three-valued logic, returning missing if x is missing.

See also ~ for bitwise not.

Examples

julia> !true
false
julia> !false
true
julia> !missing
missing
julia> .![true false true]
1×3 BitMatrix:
 0  1  0

source

!f::Function

Predicate function negation: when the argument of ! is a function, it returns a function which computes the boolean negation of f.

See also ∘.

Examples

julia> str = "∀ ε > 0, ∃ δ > 0: |x-y| < δ ⇒ |f(x)-f(y)| < ε"
"∀ ε > 0, ∃ δ > 0: |x-y| < δ ⇒ |f(x)-f(y)| < ε"
julia> filter(isletter, str)
"εδxyδfxfyε"
julia> filter(!isletter, str)
"∀  > 0, ∃  > 0: |-| <  ⇒ |()-()| < "

source

&& — Keyword

x && y

Short-circuiting boolean AND.

See also &, the ternary operator ? :, and the manual section on control flow.

Examples

julia> x = 3;
julia> x > 1 && x < 10 && x isa Int
true
julia> x < 0 && error("expected positive x")
false

source

|| — Keyword

x || y

Short-circuiting boolean OR.

See also: |, xor, &&.

Examples

julia> pi < 3 || ℯ < 3
true
julia> false || true || println("neither is true!")
true

source

Mathematical Functions

Base.isapprox — Function

isapprox(x, y; atol::Real=0, rtol::Real=atol>0 ? 0 : √eps, nans::Bool=false[, norm::Function])

Inexact equality comparison. Two numbers compare equal if their relative distance or their absolute distance is within tolerance bounds: isapprox returns true if norm(x-y) <= max(atol, rtol*max(norm(x), norm(y))). The default atol is zero and the default rtol depends on the types of x and y. The keyword argument nans determines whether or not NaN values are considered equal (defaults to false).

For real or complex floating-point values, if an atol > 0 is not specified, rtol defaults to the square root of eps of the type of x or y, whichever is bigger (least precise). This corresponds to requiring equality of about half of the significant digits. Otherwise, e.g. for integer arguments or if an atol > 0 is supplied, rtol defaults to zero.

The norm keyword defaults to abs for numeric (x,y) and to LinearAlgebra.norm for arrays (where an alternative norm choice is sometimes useful). When x and y are arrays, if norm(x-y) is not finite (i.e. ±Inf or NaN), the comparison falls back to checking whether all elements of x and y are approximately equal component-wise.

The binary operator ≈ is equivalent to isapprox with the default arguments, and x ≉ y is equivalent to !isapprox(x,y).

Note that x ≈ 0 (i.e., comparing to zero with the default tolerances) is equivalent to x == 0 since the default atol is 0. In such cases, you should either supply an appropriate atol (or use norm(x) ≤ atol) or rearrange your code (e.g. use x ≈ y rather than x - y ≈ 0). It is not possible to pick a nonzero atol automatically because it depends on the overall scaling (the “units”) of your problem: for example, in x - y ≈ 0, atol=1e-9 is an absurdly small tolerance if x is the radius of the Earth in meters, but an absurdly large tolerance if x is the radius of a Hydrogen atom in meters.

Julia 1.6

Passing the norm keyword argument when comparing numeric (non-array) arguments requires Julia 1.6 or later.

Examples

julia> isapprox(0.1, 0.15; atol=0.05)
true
julia> isapprox(0.1, 0.15; rtol=0.34)
true
julia> isapprox(0.1, 0.15; rtol=0.33)
false
julia> 0.1 + 1e-10 ≈ 0.1
true
julia> 1e-10 ≈ 0
false
julia> isapprox(1e-10, 0, atol=1e-8)
true
julia> isapprox([10.0^9, 1.0], [10.0^9, 2.0]) # using `norm`
true

source

isapprox(x; kwargs...) / ≈(x; kwargs...)

Create a function that compares its argument to x using ≈, i.e. a function equivalent to y -> y ≈ x.

The keyword arguments supported here are the same as those in the 2-argument isapprox.

Julia 1.5

This method requires Julia 1.5 or later.

source

Base.sin — Method

sin(x)

Compute sine of x, where x is in radians.

See also [sind], [sinpi], [sincos], [cis].

source

Base.cos — Method

cos(x)

Compute cosine of x, where x is in radians.

See also [cosd], [cospi], [sincos], [cis].

source

Base.Math.sincos — Method

sincos(x)

Simultaneously compute the sine and cosine of x, where x is in radians, returning a tuple (sine, cosine).

See also cis, sincospi, sincosd.

source

Base.tan — Method

tan(x)

Compute tangent of x, where x is in radians.

source

Base.Math.sind — Function

sind(x)

Compute sine of x, where x is in degrees. If x is a matrix, x needs to be a square matrix.

Julia 1.7

Matrix arguments require Julia 1.7 or later.

source

Base.Math.cosd — Function

cosd(x)

Compute cosine of x, where x is in degrees. If x is a matrix, x needs to be a square matrix.

Julia 1.7

Matrix arguments require Julia 1.7 or later.

source

Base.Math.tand — Function

tand(x)

Compute tangent of x, where x is in degrees. If x is a matrix, x needs to be a square matrix.

Julia 1.7

Matrix arguments require Julia 1.7 or later.

source

Base.Math.sincosd — Function

sincosd(x)

Simultaneously compute the sine and cosine of x, where x is in degrees.

Julia 1.3

This function requires at least Julia 1.3.

source

Base.Math.sinpi — Function

sinpi(x)

Compute $\sin(\pi x)$ more accurately than sin(pi*x), especially for large x.

See also sind, cospi, sincospi.

source

Base.Math.cospi — Function

cospi(x)

Compute $\cos(\pi x)$ more accurately than cos(pi*x), especially for large x.

source

Base.Math.sincospi — Function

sincospi(x)

Simultaneously compute sinpi(x) and cospi(x) (the sine and cosine of π*x, where x is in radians), returning a tuple (sine, cosine).

Julia 1.6

This function requires Julia 1.6 or later.

See also: cispi, sincosd, sinpi.

source

Base.sinh — Method

sinh(x)

Compute hyperbolic sine of x.

source

Base.cosh — Method

cosh(x)

Compute hyperbolic cosine of x.

source

Base.tanh — Method

tanh(x)

Compute hyperbolic tangent of x.

source

Base.asin — Method

asin(x)

Compute the inverse sine of x, where the output is in radians.

source

Base.acos — Method

acos(x)

Compute the inverse cosine of x, where the output is in radians

source

Base.atan — Method

atan(y)
atan(y, x)

Compute the inverse tangent of y or y/x, respectively.

For one argument, this is the angle in radians between the positive x-axis and the point (1, y), returning a value in the interval $[-\pi/2, \pi/2]$.

For two arguments, this is the angle in radians between the positive x-axis and the point (x, y), returning a value in the interval $[-\pi, \pi]$. This corresponds to a standard atan2 function. Note that by convention atan(0.0,x) is defined as $\pi$ and atan(-0.0,x) is defined as $-\pi$ when x < 0.

source

Base.Math.asind — Function

asind(x)

Compute the inverse sine of x, where the output is in degrees. If x is a matrix, x needs to be a square matrix.

Julia 1.7

Matrix arguments require Julia 1.7 or later.

source

Base.Math.acosd — Function

acosd(x)

Compute the inverse cosine of x, where the output is in degrees. If x is a matrix, x needs to be a square matrix.

Julia 1.7

Matrix arguments require Julia 1.7 or later.

source

Base.Math.atand — Function

atand(y)
atand(y,x)

Compute the inverse tangent of y or y/x, respectively, where the output is in degrees.

Julia 1.7

The one-argument method supports square matrix arguments as of Julia 1.7.

source

Base.Math.sec — Method

sec(x)

Compute the secant of x, where x is in radians.

source

Base.Math.csc — Method

csc(x)

Compute the cosecant of x, where x is in radians.

source

Base.Math.cot — Method

cot(x)

Compute the cotangent of x, where x is in radians.

source

Base.Math.secd — Function

secd(x)

Compute the secant of x, where x is in degrees.

source

Base.Math.cscd — Function

cscd(x)

Compute the cosecant of x, where x is in degrees.

source

Base.Math.cotd — Function

cotd(x)

Compute the cotangent of x, where x is in degrees.

source

Base.Math.asec — Method

asec(x)

Compute the inverse secant of x, where the output is in radians.

source

Base.Math.acsc — Method

acsc(x)

Compute the inverse cosecant of x, where the output is in radians.

source

Base.Math.acot — Method

acot(x)

Compute the inverse cotangent of x, where the output is in radians.

source

Base.Math.asecd — Function

asecd(x)

Compute the inverse secant of x, where the output is in degrees. If x is a matrix, x needs to be a square matrix.

Julia 1.7

Matrix arguments require Julia 1.7 or later.

source

Base.Math.acscd — Function

acscd(x)

Compute the inverse cosecant of x, where the output is in degrees. If x is a matrix, x needs to be a square matrix.

Julia 1.7

Matrix arguments require Julia 1.7 or later.

source

Base.Math.acotd — Function

acotd(x)

Compute the inverse cotangent of x, where the output is in degrees. If x is a matrix, x needs to be a square matrix.

Julia 1.7

Matrix arguments require Julia 1.7 or later.

source

Base.Math.sech — Method

sech(x)

Compute the hyperbolic secant of x.

source

Base.Math.csch — Method

csch(x)

Compute the hyperbolic cosecant of x.

source

Base.Math.coth — Method

coth(x)

Compute the hyperbolic cotangent of x.

source

Base.asinh — Method

asinh(x)

Compute the inverse hyperbolic sine of x.

source

Base.acosh — Method

acosh(x)

Compute the inverse hyperbolic cosine of x.

source

Base.atanh — Method

atanh(x)

Compute the inverse hyperbolic tangent of x.

source

Base.Math.asech — Method

asech(x)

Compute the inverse hyperbolic secant of x.

source

Base.Math.acsch — Method

acsch(x)

Compute the inverse hyperbolic cosecant of x.

source

Base.Math.acoth — Method

acoth(x)

Compute the inverse hyperbolic cotangent of x.

source

Base.Math.sinc — Function

sinc(x)

Compute $\sin(\pi x) / (\pi x)$ if $x \neq 0$, and $1$ if $x = 0$.

See also cosc, its derivative.

source

Base.Math.cosc — Function

cosc(x)

Compute $\cos(\pi x) / x - \sin(\pi x) / (\pi x^2)$ if $x \neq 0$, and $0$ if $x = 0$. This is the derivative of sinc(x).

source

Base.Math.deg2rad — Function

deg2rad(x)

Convert x from degrees to radians.

See also: rad2deg, sind.

Examples

julia> deg2rad(90)
1.5707963267948966

source

Base.Math.rad2deg — Function

rad2deg(x)

Convert x from radians to degrees.

Examples

julia> rad2deg(pi)
180.0

source

Base.Math.hypot — Function

hypot(x, y)

Compute the hypotenuse $\sqrt{|x|^2+|y|^2}$ avoiding overflow and underflow.

This code is an implementation of the algorithm described in: An Improved Algorithm for hypot(a,b) by Carlos F. Borges The article is available online at ArXiv at the link https://arxiv.org/abs/1904.09481

hypot(x...)

Compute the hypotenuse $\sqrt{\sum |x_i|^2}$ avoiding overflow and underflow.

See also norm in the LinearAlgebra standard library.

Examples

julia> a = Int64(10)^10;
julia> hypot(a, a)
1.4142135623730951e10
julia> √(a^2 + a^2) # a^2 overflows
ERROR: DomainError with -2.914184810805068e18:
sqrt will only return a complex result if called with a complex argument. Try sqrt(Complex(x)).
Stacktrace:
[...]
julia> hypot(3, 4im)
5.0
julia> hypot(-5.7)
5.7
julia> hypot(3, 4im, 12.0)
13.0
julia> using LinearAlgebra
julia> norm([a, a, a, a]) == hypot(a, a, a, a)
true

source

Base.log — Method

log(x)

Compute the natural logarithm of x. Throws DomainError for negative Real arguments. Use complex negative arguments to obtain complex results.

See also [log1p], [log2], [log10].

Examples

julia> log(2)
0.6931471805599453
julia> log(-3)
ERROR: DomainError with -3.0:
log will only return a complex result if called with a complex argument. Try log(Complex(x)).
Stacktrace:
 [1] throw_complex_domainerror(::Symbol, ::Float64) at ./math.jl:31
[...]

source

Base.log — Method

log(b,x)

Compute the base b logarithm of x. Throws DomainError for negative Real arguments.

Examples

julia> log(4,8)
1.5
julia> log(4,2)
0.5
julia> log(-2, 3)
ERROR: DomainError with -2.0:
log will only return a complex result if called with a complex argument. Try log(Complex(x)).
Stacktrace:
 [1] throw_complex_domainerror(::Symbol, ::Float64) at ./math.jl:31
[...]
julia> log(2, -3)
ERROR: DomainError with -3.0:
log will only return a complex result if called with a complex argument. Try log(Complex(x)).
Stacktrace:
 [1] throw_complex_domainerror(::Symbol, ::Float64) at ./math.jl:31
[...]

Note

If b is a power of 2 or 10, log2 or log10 should be used, as these will typically be faster and more accurate. For example,

julia> log(100,1000000)
2.9999999999999996
julia> log10(1000000)/2
3.0

source

Base.log2 — Function

log2(x)

Compute the logarithm of x to base 2. Throws DomainError for negative Real arguments.

See also: exp2, ldexp, ispow2.

Examples

julia> log2(4)
2.0
julia> log2(10)
3.321928094887362
julia> log2(-2)
ERROR: DomainError with -2.0:
log2 will only return a complex result if called with a complex argument. Try log2(Complex(x)).
Stacktrace:
 [1] throw_complex_domainerror(f::Symbol, x::Float64) at ./math.jl:31
[...]

source

Base.log10 — Function

log10(x)

Compute the logarithm of x to base 10. Throws DomainError for negative Real arguments.

Examples

julia> log10(100)
2.0
julia> log10(2)
0.3010299956639812
julia> log10(-2)
ERROR: DomainError with -2.0:
log10 will only return a complex result if called with a complex argument. Try log10(Complex(x)).
Stacktrace:
 [1] throw_complex_domainerror(f::Symbol, x::Float64) at ./math.jl:31
[...]

source

Base.log1p — Function

log1p(x)

Accurate natural logarithm of 1+x. Throws DomainError for Real arguments less than -1.

Examples

julia> log1p(-0.5)
-0.6931471805599453
julia> log1p(0)
0.0
julia> log1p(-2)
ERROR: DomainError with -2.0:
log1p will only return a complex result if called with a complex argument. Try log1p(Complex(x)).
Stacktrace:
 [1] throw_complex_domainerror(::Symbol, ::Float64) at ./math.jl:31
[...]

source

Base.Math.frexp — Function

frexp(val)

Return (x,exp) such that x has a magnitude in the interval $[1/2, 1)$ or 0, and val is equal to $x \times 2^{exp}$.

Examples

julia> frexp(12.8)
(0.8, 4)

source

Base.exp — Method

exp(x)

Compute the natural base exponential of x, in other words $ℯ^x$.

See also exp2, exp10 and cis.

Examples

julia> exp(1.0)
2.718281828459045
julia> exp(im * pi) ≈ cis(pi)
true

source

Base.exp2 — Function

exp2(x)

Compute the base 2 exponential of x, in other words $2^x$.

See also ldexp, <<.

Examples

julia> exp2(5)
32.0
julia> 2^5
32
julia> exp2(63) > typemax(Int)
true

source

Base.exp10 — Function

exp10(x)

Compute the base 10 exponential of x, in other words $10^x$.

Examples

julia> exp10(2)
100.0
julia> 10^2
100

source

Base.Math.ldexp — Function

ldexp(x, n)

Compute $x \times 2^n$.

Examples

julia> ldexp(5., 2)
20.0

source

Base.Math.modf — Function

modf(x)

Return a tuple (fpart, ipart) of the fractional and integral parts of a number. Both parts have the same sign as the argument.

Examples

julia> modf(3.5)
(0.5, 3.0)
julia> modf(-3.5)
(-0.5, -3.0)

source

Base.expm1 — Function

expm1(x)

Accurately compute $e^x-1$. It avoids the loss of precision involved in the direct evaluation of exp(x)-1 for small values of x.

Examples

julia> expm1(1e-16)
1.0e-16
julia> exp(1e-16) - 1
0.0

source

Base.round — Method

round([T,] x, [r::RoundingMode])
round(x, [r::RoundingMode]; digits::Integer=0, base = 10)
round(x, [r::RoundingMode]; sigdigits::Integer, base = 10)

Rounds the number x.

Without keyword arguments, x is rounded to an integer value, returning a value of type T, or of the same type of x if no T is provided. An InexactError will be thrown if the value is not representable by T, similar to convert.

If the digits keyword argument is provided, it rounds to the specified number of digits after the decimal place (or before if negative), in base base.

If the sigdigits keyword argument is provided, it rounds to the specified number of significant digits, in base base.

The RoundingMode r controls the direction of the rounding; the default is RoundNearest, which rounds to the nearest integer, with ties (fractional values of 0.5) being rounded to the nearest even integer. Note that round may give incorrect results if the global rounding mode is changed (see rounding).

Examples

julia> round(1.7)
2.0
julia> round(Int, 1.7)
2
julia> round(1.5)
2.0
julia> round(2.5)
2.0
julia> round(pi; digits=2)
3.14
julia> round(pi; digits=3, base=2)
3.125
julia> round(123.456; sigdigits=2)
120.0
julia> round(357.913; sigdigits=4, base=2)
352.0