diff --git a/Project.toml b/Project.toml
index db5c904..9ef689f 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,21 +1,34 @@
 name = "PTYQoL"
 uuid = "551ad714-b11a-4605-8871-12721def4e72"
 authors = ["Tianyi Pu <912396513@qq.com> and contributors"]
-version = "0.1.2"
+version = "0.1.3"
 
 [weakdeps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
+CircularArrays = "7a955b69-7140-5f4e-a0ed-f168c5e2e749"
+ContinuumArrays = "7ae1f121-cc2c-504b-ac30-9b923412ae5c"
+IntervalSets = "8197267c-284f-5f27-9208-e0e47529a953"
+QuasiArrays = "c4ea9172-b204-11e9-377d-29865faadc5c"
+ClassicalOrthogonalPolynomials = "b30e2e7b-c4ee-47da-9d5f-2c5c27239acd"
 
 [extensions]
 PTYQoLLinearAlgebraExt = "LinearAlgebra"
+PTYQoLCircularArraysExt = "CircularArrays"
+PTYQoLContinuumArraysExt = "ContinuumArrays"
+PTYQoLIntervalSetsExt = "IntervalSets"
+PTYQoLQuasiArraysExt = "QuasiArrays"
+PTYQoLClassicalOrthogonalPolynomialsExt = "ClassicalOrthogonalPolynomials"
 
 [compat]
 julia = "1"
 
 [extras]
+ContinuumArrays = "7ae1f121-cc2c-504b-ac30-9b923412ae5c"
 Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
+DomainSets = "5b8099bc-c8ec-5219-889f-1d9e522a28bf"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+ClassicalOrthogonalPolynomials = "b30e2e7b-c4ee-47da-9d5f-2c5c27239acd"
 
 [targets]
-test = ["Test", "LinearAlgebra", "Documenter"]
+test = ["Test", "LinearAlgebra", "Documenter", "DomainSets", "ContinuumArrays", "ClassicalOrthogonalPolynomials"]
diff --git a/ext/PTYQoLCircularArraysExt.jl b/ext/PTYQoLCircularArraysExt.jl
new file mode 100644
index 0000000..1a5edee
--- /dev/null
+++ b/ext/PTYQoLCircularArraysExt.jl
@@ -0,0 +1,12 @@
+module PTYQoLCircularArraysExt
+
+import CircularArrays: CircularArray
+"""
+    CircularMatrix{T,A} <: AbstractVector{T}
+    
+Two-dimensional array backed by an `AbstractArray{T, 2}` of type `A` with fixed size and circular indexing.
+Alias for [`CircularArray{T,2,A}`](@ref).
+"""
+const CircularMatrix{T} = CircularArray{T, 2}
+
+end
diff --git a/ext/PTYQoLClassicalOrthogonalPolynomialsExt.jl b/ext/PTYQoLClassicalOrthogonalPolynomialsExt.jl
new file mode 100644
index 0000000..434e20f
--- /dev/null
+++ b/ext/PTYQoLClassicalOrthogonalPolynomialsExt.jl
@@ -0,0 +1,12 @@
+module PTYQoLClassicalOrthogonalPolynomialsExt
+
+import ClassicalOrthogonalPolynomials: AbstractJacobi, Jacobi, Chebyshev, Legendre, Ultraspherical
+
+AbstractJacobi{T}(a::Jacobi) where T = Jacobi{T}(a)
+AbstractJacobi{T}(::Chebyshev{kind}) where T where kind = Chebyshev{kind,T}()
+AbstractJacobi{T}(::Legendre) where T = Legendre{T}()
+AbstractJacobi{T}(a::Ultraspherical) where T = Ultraspherical{T}(a)
+
+Jacobi{T}(a::Jacobi) where T = Jacobi(T(a.a), T(a.b))
+
+end
\ No newline at end of file
diff --git a/ext/PTYQoLContinuumArraysExt.jl b/ext/PTYQoLContinuumArraysExt.jl
new file mode 100644
index 0000000..36a3061
--- /dev/null
+++ b/ext/PTYQoLContinuumArraysExt.jl
@@ -0,0 +1,32 @@
+module PTYQoLContinuumArraysExt
+
+import Base: union, Fix2, isempty
+import ContinuumArrays: AbstractInterval, BroadcastQuasiVector, Interval, Inclusion, endpoints, isleftclosed, isrightclosed
+
+function union(x::BroadcastQuasiVector{T, <:Fix2{typeof(^), <:Number}, <:Tuple{Inclusion{T, <:AbstractInterval}}}) where T
+    p = x.f.x
+    I = first(x.args).domain
+    a, b = endpoints(I)
+    if isempty(I) || b ≤ 0
+        Inclusion(Interval{:open, :open}(zero(T), zero(T)))
+    elseif iszero(p)
+        Inclusion(Interval{:closed, :closed}(one(T), one(T)))
+    else
+        R = ifelse(isrightclosed(I), :closed, :open)
+        if a ≥ 0
+            L = ifelse(isleftclosed(I), :closed, :open)
+        else
+            L = :closed
+            a = zero(T)
+        end
+        if p < 0
+            Inclusion(Interval{R, L}(b^p, a^p))
+        else
+            Inclusion(Interval{L, R}(a^p, b^p))
+        end
+    end            
+end
+
+isempty(a::Inclusion) = isempty(a.domain)
+
+end
\ No newline at end of file
diff --git a/ext/PTYQoLIntervalSetsExt.jl b/ext/PTYQoLIntervalSetsExt.jl
new file mode 100644
index 0000000..d7e729f
--- /dev/null
+++ b/ext/PTYQoLIntervalSetsExt.jl
@@ -0,0 +1,8 @@
+module PTYQoLIntervalSetsExt
+
+import IntervalSets: Domain
+import Base: union
+
+union(a::Domain) = a
+
+end
\ No newline at end of file
diff --git a/ext/PTYQoLQuasiArraysExt.jl b/ext/PTYQoLQuasiArraysExt.jl
new file mode 100644
index 0000000..49a385c
--- /dev/null
+++ b/ext/PTYQoLQuasiArraysExt.jl
@@ -0,0 +1,10 @@
+module PTYQoLQuasiArraysExt
+
+import Base: union, Fix2, Fix1, broadcasted, literal_pow
+import QuasiArrays: BroadcastQuasiVector, LazyQuasiArrayStyle, AbstractQuasiVector
+
+broadcasted(::LazyQuasiArrayStyle{1}, ::typeof(^), x::AbstractQuasiVector, b::Number) = Fix2(^, b).(x)
+broadcasted(::LazyQuasiArrayStyle{1}, ::typeof(^), a::Number, x::AbstractQuasiVector) = Fix1(^, a).(x)
+broadcasted(::typeof(literal_pow), ::typeof(^), x::AbstractQuasiVector, ::Val{b}) where b = Fix2(^, b).(x)
+
+end
\ No newline at end of file
diff --git a/src/Utils.jl b/src/Utils.jl
index cdfe249..0dc4c18 100644
--- a/src/Utils.jl
+++ b/src/Utils.jl
@@ -115,4 +115,8 @@ export ln
 
 The same as `log` but only accepts one argument.
 """
-ln(x::Number) = log(x)
\ No newline at end of file
+ln(x::Number) = log(x)
+
+export precision_convert
+precision_convert(::Type{BigFloat}, x, precision) = BigFloat(x, precision = precision)
+precision_convert(T, x, precision) = convert(T, x)
\ No newline at end of file
diff --git a/test/runtests.jl b/test/runtests.jl
index 09a262d..a5608dd 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -54,6 +54,33 @@ end
     @test ln(1) == 0 # just for coverage
 end
 
+@testset "precision_convert" begin
+    setprecision(256)
+    x = precision_convert(BigFloat, BigFloat(1), 128)
+    @test precision(x) == 128
+end
+
+@testset "Extensions" begin
+    @testset "IntervalSets" begin
+        using DomainSets
+        @test union(ChebyshevInterval()) ≡ ChebyshevInterval()
+    end
+    @testset "QuasiArrays" begin
+        using ContinuumArrays
+        @test union(Inclusion(0..1).^2) == Inclusion(0..1) == union(Inclusion(-1..1).^1.0) == union(Inclusion(1..Inf).^(-0.5))
+        @test isempty(union(Inclusion(-1..0).^1.5))
+        @test union(Inclusion(0..1).^0) == Inclusion(1..1)
+    end
+    @testset "ClassicalOrthogonalPolynomials" begin
+        using ClassicalOrthogonalPolynomials
+        using ClassicalOrthogonalPolynomials: AbstractJacobi
+        @test AbstractJacobi{Float32}(Jacobi(1,1)) isa Jacobi{Float32}
+        @test AbstractJacobi{Float16}(ChebyshevU()) isa ChebyshevU{Float16}
+        @test AbstractJacobi{BigFloat}(Legendre()) isa Legendre{BigFloat}
+        @test AbstractJacobi{Float32}(Ultraspherical(2)) isa Ultraspherical{Float32}
+    end
+end
+
 DocMeta.setdocmeta!(PTYQoL, :DocTestSetup, :(using PTYQoL); recursive=true)
 @testset "Docs" begin
 	doctest(PTYQoL)