missing fdlibm functions about julia HOT 12 CLOSED

Are there implementations available for those five functions? IIRC you said they were all rounding functions. Maybe LLVM has trustworthy intrinsics for those operations — rounding is pretty unambiguous.

from julia.

No, LLVM does not have those as intrinsics, and as far as I can tell the intrinsics LLVM does have just call libm.
We can get implementations from BSD.

from julia.

Oh, llvm-config has us linking with -lm, so we won't be able to remove it. Not a big deal.

from julia.

Those two fixed, but we are also missing tgamma.

from julia.

tgamma is called gamma — I added it the other day. We can make tgamma be an alias, but that seems like a historical accident due to a mistake that it would be fairly silly to inherit from C.

from julia.

Sure, it's called gamma in julia, but what we're missing is the actual implementation of tgamma in fdlibm:

julia> gamma(2)
dlsym: /home/jeff/src/julia2/julia/lib/libfdm.so: undefined symbol: tgamma

from julia.

That's weird. Mine work — I tested them before making that commit:

julia> gamma(4.5)
11.6317283965674498

julia> gamma(float32(4.5))
11.63172817

from julia.

It must be finding the symbol from libm somehow. grep tgamma * in fdlibm/ is empty. Maybe try ldd and nm on libfdm.dylib.

from julia.

Ah, yeah, that's really strange. This would be found if we could force LLVM not to link against libm since then there would be no tgamma at all to link to.

My understanding is that gamma is deprecated in favor of tgamma because historically, on some systems gamma was the log-gamma function whereas on other systems it was just the gamma function. The only way to guarantee that the implementation and the intended usage were in agreement was to deprecate gamma and have tgamma replace it as unambiguously meaning the non-log gamma function.

So as long as the fdlibm we include has a gamma function that means tgamma, we can just use its gamma function. But given the mislinking above, I'm a little afraid to do that. If we can get rid of the -lm under llvm-config, that would work. Alternatively, we can just fork fdlibm's code and rename gamma to tgamma everywhere.

from julia.

Let me know if 9d1009f fixes this for you, Jeff. I can't test since it was already working for me.

from julia.

Stefan, that commit is shameful. You didn't even look at the code. fdlibm uses the old naming convention where "gamma" means log-gamma. Its "gamma" just calls lgamma.

from julia.

Ugh. Sorry. That is really embarrassing. I was somehow still linking against the libm version, so I was getting apparently correct results. I'll endeavor to find a working tgamma implementation to plug in here...

from julia.