User API

These are functions you can use on any ThickNumber subtype when writing your code. Generally you shouldn't need to implement these directly (they all have default implementations), although you can of course specialize them as needed as long as your implementation does not violate the interface requirements.

Types

ThickNumbers.valuetype — Function

valuetype(::Type{<:ThickNumber})

Return the type of the numbers in the span, i.e., the T in ThickNumber{T}.

Examples

julia> valuetype(Interval{Float64})
Float64

Query functions

API functions from the Interval Arithmetic Standard (IEEE Std 1788-2015), Table 9.2 are supported. One (deliberate) exception is inf and sup, which are replaced by loval and hival: inf and sup have well-defined mathematical meanings that may not be appropriate for all ThickNumber subtypes (e.g., gaussian random variables don't have finite lower and upper bounds). If you are creating an interval arithmetic package, of course you can choose to define

inf(x::MyInterval) = loval(x)
sup(x::MyInterval) = hival(x)

in order to comply with the standard.

ThickNumbers.mid — Function

mid(x::ThickNumber)

The midpoint of the span of x. Required by IEEE Std 1788-2015, Table 9.2.

Default implementation

The default implementation is

mid(x::ThickNumber) = (loval(x) + hival(x))/2

ThickNumbers.mag — Function

mag(x::ThickNumber)

The maximum absolute value of x. Required by IEEE Std 1788-2015, Table 9.2.

Default implementation

The default implementation is

mag(x::ThickNumber) = max(abs(loval(x)), abs(hival(x)))

ThickNumbers.mig — Function

mig(x::ThickNumber)

The minimum absolute value of x. Required by IEEE Std 1788-2015, Table 9.2.

Default implementation

The default implementation checks to see if the set contains zero, and if so returns zero. Otherwise, it returns the minimum absolute value of the endpoints:

mig(x::ThickNumber) = zero(T) ∈ x ? zero(T) : min(abs(loval(x)), abs(hival(x)))

ThickNumbers.rad — Function

rad(x::ThickNumber)

Half the width of the span of x. Required by IEEE Std 1788-2015, Table 9.2.

Default implementation

The default implementation is

rad(x::ThickNumber) = wid(x)/2

ThickNumbers.wid — Function

wid(x::ThickNumber)

The width of the span of x. Required by IEEE Std 1788-2015, Table 9.2.

Default implementation

The default implementation is

wid(x::ThickNumber) = hival(x) - loval(x)

ThickNumbers.isfinite_tn — Function

isfinite_tn(x::ThickNumber)

Returns true if all values in x are finite, false otherwise.

ThickNumbers.isinf_tn — Function

isinf_tn(x::ThickNumber)

Returns true if any value in x is infinite, false otherwise.

ThickNumbers.isnan_tn — Function

isnan_tn(x::ThickNumber)

Returns true if any value in x is NaN, false otherwise.

Comparison operators

ThickNumbers.iseq_tn — Function

iseq_tn(a::ThickNumber, b::ThickNumber)
a ≐ b  (`\doteq`-TAB`)

Returns true if a and b are both empty or both loval and hival are equal in the sense of ==. It is false otherwise.

ThickNumbers.isequal_tn — Function

isequal_tn(a::ThickNumber, b::ThickNumber)

Returns true if a and b are both empty or both loval and hival are equal in the sense of isequal. It is false otherwise.

ThickNumbers.isapprox_tn — Function

isapprox_tn(a::ThickNumber, b::ThickNumber; atol=0, rtol::Real=atol>0 ? 0 : √eps)
a ⩪ b (`\dotsim`-TAB)

Returns true if a and b are both empty or both loval and hival are approximately equal (≈). It is false otherwise.

ThickNumbers.isless_tn — Function

isless_tn(a::ThickNumber, b::ThickNumber)

Returns true if isless(hival(a), loval(b)), false otherwise. See also ≺.

ThickNumbers.:≺ — Function

a ≺ b

Returns true if hival(a) < loval(b), false otherwise. Use \prec-TAB to type.

ThickNumbers.:≻ — Function

a ≻ b

Returns true if loval(a) > hival(b), false otherwise. Use \succ-TAB to type.

ThickNumbers.:⪯ — Function

a ≼ b

Returns true if hival(a) ≤ loval(b), false otherwise. Use \preceq-TAB to type.

ThickNumbers.:⪰ — Function

a ≽ b

Returns true if loval(a) ≥ hival(b), false otherwise. Use \succeq-TAB to type.

Set operations

See also IntervalSets for a more flexible way of supporting intervals as sets.

Base.in — Method

in(x::Real, a::ThickNumber)

Returns true if x is in the span of a (i.e., between loval(a) and hival(a)), false otherwise.

ThickNumbers.hull — Function

hull(a::ThickNumber, b::ThickNumber, c::ThickNumber...)

Construct a ThickNumber containing a, b, and c....

Base.isempty — Method

isempty(x::ThickNumber)

Returns true if hival(x) < loval(x) is empty, false otherwise.

ThickNumbers.issubset_tn — Function

issubset_tn(a::ThickNumber, b::ThickNumber)
⫃(a::ThickNumber, b::ThickNumber)

Returns true if a is a subset of b, false otherwise.

See documentation for why this is not just ⊆

ThickNumbers.issupset_tn — Function

issupset_tn(a::ThickNumber, b::ThickNumber)
⫄(a::ThickNumber, b::ThickNumber)

The converse of issubset_tn.

ThickNumbers.is_strict_subset_tn — Function

is_strict_subset_tn(a::ThickNumber, b::ThickNumber)
⪽(a::ThickNumber, b::ThickNumber)

Returns true if a is a strict subset of b, false otherwise. a is a strict subset if a is a subset of b not equal to b.

See documentation for why this is not just ⊂.

ThickNumbers.is_strict_supset_tn — Function

is_strict_supset_tn(a::ThickNumber, b::ThickNumber)
⪾(a::ThickNumber, b::ThickNumber)

The converse of is_strict_subset_tn.

Also supported are Base's:

isdisjoint
intersect

Operations with real numbers

clamp(::Real, ::ThickNumber)