exp of some NaNs is negative

[aplavin]

Presumably, negative exp should never happen, and this should return a NaN instead?

julia> reinterpret(Float64, 0x7ffbb14880000000)
NaN

julia> exp(reinterpret(Float64, 0x7ffbb14880000000))
-9.627794635514914e-309

[oscardssmith]

yeah, this is bad.

[inkydragon]

And more...

julia> wNaN = reinterpret(Float64, 0x7ffbb14880000000)
NaN

julia> bad_func = [cosh, sinh, tanh, exp, exp10, exp2]
6-element Vector{Function}:
 cosh (generic function with 12 methods)
 sinh (generic function with 12 methods)
 tanh (generic function with 12 methods)
 exp (generic function with 13 methods)
 exp10 (generic function with 7 methods)
 exp2 (generic function with 8 methods)

julia> [ f(wNaN) for f in bad_func ]
6-element Vector{Float64}:
 -5.193297311884955e307
  5.193297311884955e307
  1.0
 -9.627794635514914e-309
 -9.627794635514914e-309
 -9.627794635514914e-309

Test script

c23_libm_unary = [
    #= F.10.1 Trigonometric functions =#
        acos, asin, atan,
        cos, sin, tan,
        # acospi, asinpi, atanpi,  # not-impl
        cospi, sinpi, tanpi,
    #= F.10.2 Hyperbolic functions =#
        acosh, asinh, atanh,
        cosh, sinh, tanh,
    #= F.10.3 Exponential and logarithmic functions =#
        exp, exp10,
        # exp10m1,
        exp2,
        # exp2m1,
        expm1,
        # frexp,  # NOTE: ldexp(x, n), test as unary
        f->ldexp(f, 1),
        # modf  # NOTE: ret (x,exp)
        f->modf(f)[1],
        f->modf(f)[2],
        # ilogb,
        log, log10,
        # log10p1, logp1, 
        log2,
        # log2p1, logb,
    #= F.10.4 Power and absolute value functions =#
        cbrt,
        abs, # (fabs)
        # rsqrt,
        sqrt,
    #= F.10.5 Error and gamma functions =#
        # erf, erfc, lgamma, tgamma,
    #= F.10.6 Nearest integer functions =#
        ceil, floor,
        # nearbyint, rint,
        round,
        # roundeven,
        trunc,
]

c23_libm_binary = [
    #= F.10.1 Trigonometric functions =#
        # atan2, atan2pi,  # not-impl
    #= F.10.2 Hyperbolic functions (no binary func) =#
    #= F.10.3 Exponential and logarithmic functions =#
        # ldexp,  # NOTE: test as unary
        # scalbn,
    #= F.10.4 Power and absolute value functions =#
        # compoundn,
        hypot,
        ^, # (pow, pown, powr,)
        # rootn,
    #= F.10.5 Error and gamma functions (no binary func) =#
    #= F.10.6 Nearest integer functions (no binary func) =#
    #= F.10.7 Remainder functions =#
        mod,  # (fmod)
        rem,  # (remainder)
        # remquo,
]

wNaN16 = reinterpret(Float16, reinterpret(UInt16, NaN16)+0x4)
wNaN32 = reinterpret(Float32, reinterpret(UInt32, NaN32)+0x8)
wNaN64 = reinterpret(Float64, 0x7ffbb14880000000)

@info "Test c23_libm_unary($(length(c23_libm_unary)))"
[ isnan(f(NaN)) for f in c23_libm_unary] |> all
[ isnan(f(wNaN16)) for f in c23_libm_unary] |> all
[ isnan(f(wNaN32)) for f in c23_libm_unary] |> all
[ isnan(f(wNaN64)) for f in c23_libm_unary] |> all
for f in c23_libm_unary
    isnan(f(wNaN64)) || println(f)
end

@info "Test c23_libm_binary($(length(c23_libm_binary)))"
[ isnan(f2(NaN,NaN)) for f2 in c23_libm_binary] |> all
[ isnan(f2(wNaN16,NaN)) for f2 in c23_libm_binary] |> all
[ isnan(f2(wNaN32,NaN)) for f2 in c23_libm_binary] |> all
[ isnan(f2(wNaN64,NaN)) for f2 in c23_libm_binary] |> all
for f2 in c23_libm_binary
    isnan(f2(wNaN64, NaN)) || println(f)
    isnan(f2(NaN, wNaN64)) || println(f)
    isnan(f2(wNaN64, wNaN64)) || println(f)
end

[oscardssmith]

all of those are fixed by my pr, right?

[inkydragon]

all of those are fixed by my pr, right?

I guess so, since all those functions are related to exp.