computing ceil at compile time

[bioinfornatics]

Hi,
with ldc maybe that works with an another compiler, i fail to 
compute std.math.ceil at compile time

minimal example: http://paste.fedoraproject.org/56332/52482751


$ ldc2 compute.d main.d -of ok
/usr/include/d/std/math.d(2471): Error: ceill cannot be 
interpreted at compile time, because it has no available source 
code
compute.d(5):        called from here: ceil(cast(real)i)
compute.d(8):        called from here: foo(2.4F)