Merge pull request #9844 from eschnett/mpfr-float16

Add `convert(Float16, BigFloat)`
JuliaLang · Jan 22, 2015 · 180a6c5 · 180a6c5
2 parents bb05118 + c29e190
commit 180a6c5
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diff --git a/base/mpfr.jl b/base/mpfr.jl
@@ -174,11 +174,16 @@ convert(::Type{Float64}, x::BigFloat) =
     ccall((:mpfr_get_d,:libmpfr), Float64, (Ptr{BigFloat},Int32), &x, ROUNDING_MODE[end])
 convert(::Type{Float32}, x::BigFloat) =
     ccall((:mpfr_get_flt,:libmpfr), Float32, (Ptr{BigFloat},Int32), &x, ROUNDING_MODE[end])
+# TODO: avoid double rounding
+convert(::Type{Float16}, x::BigFloat) = convert(Float16, convert(Float32, x))
 
 call(::Type{Float64}, x::BigFloat, r::RoundingMode) =
     ccall((:mpfr_get_d,:libmpfr), Float64, (Ptr{BigFloat},Int32), &x, to_mpfr(r))
 call(::Type{Float32}, x::BigFloat, r::RoundingMode) =
     ccall((:mpfr_get_flt,:libmpfr), Float32, (Ptr{BigFloat},Int32), &x, to_mpfr(r))
+# TODO: avoid double rounding
+call(::Type{Float16}, x::BigFloat, r::RoundingMode) =
+    convert(Float16, call(Float32, x, r))
 
 promote_rule{T<:Real}(::Type{BigFloat}, ::Type{T}) = BigFloat
 promote_rule{T<:FloatingPoint}(::Type{BigInt},::Type{T}) = BigFloat

diff --git a/test/mpfr.jl b/test/mpfr.jl
@@ -149,6 +149,7 @@ y = BigFloat(1)
 # convert from
 @test convert(Float64, BigFloat(0.5)) == 0.5
 @test convert(Float32, BigFloat(0.5)) == float32(0.5)
+@test convert(Float16, BigFloat(0.5)) == float16(0.5)
 
 # exponent
 x = BigFloat(0)