Merge pull request #5036 from simonbyrne/bigrealminmax

add realmin realmax for BigFloat

base/mpfr.jl

@@ -19,7 +19,8 @@ import
         gamma, lgamma, digamma, erf, erfc, zeta, log1p, airyai, iceil, ifloor,
         itrunc, eps, signbit, sin, cos, tan, sec, csc, cot, acos, asin, atan,
         cosh, sinh, tanh, sech, csch, coth, acosh, asinh, atanh, atan2,
-        serialize, deserialize, inf, nan, hash, cbrt, typemax, typemin
+        serialize, deserialize, inf, nan, hash, cbrt, typemax, typemin,
+        realmin, realmax
 
 import Base.Math.lgamma_r
 
@@ -687,6 +688,9 @@ end
 
 eps(::Type{BigFloat}) = nextfloat(BigFloat(1)) - BigFloat(1)
 
+realmin(::Type{BigFloat}) = nextfloat(zero(BigFloat))
+realmax(::Type{BigFloat}) = prevfloat(inf(BigFloat))
+
 function with_bigfloat_precision(f::Function, precision::Integer)
     old_precision = get_bigfloat_precision()
     set_bigfloat_precision(precision)

test/mpfr.jl

@@ -341,6 +341,14 @@ end
 x = eps(BigFloat)
 @test BigFloat(1) + x == BigFloat(1) + prevfloat(x)
 
+# realmin/realmax
+x = realmin(BigFloat)
+@test x > 0 
+@test prevfloat(x) == 0
+x = realmax(BigFloat)
+@test !isinf(x)
+@test isinf(nextfloat(x))
+
 # factorial
 with_bigfloat_precision(256) do
     x = BigFloat(42)