Fix round

[omarocegueda]

This is a follow-up to #493.

Apparently, round is not defined in c++98:
http://stackoverflow.com/questions/485525/round-for-float-in-c

which causes this error:
http://nipy.bic.berkeley.edu/builders/dipy-py2.7-win32/builds/124/steps/shell_5/logs/stdio

Using floor(x+0.5) may not be consistent with numpy, we also need to consider rounding to nearest even:
http://mathematica.stackexchange.com/questions/2116/why-round-to-even-integers

This solution uses the same procedure as for "dpy_log2", by borrowing code from numpy:
https://github.com/numpy/numpy/blob/master/numpy/core/src/npymath/npy_math.c.src

The code now builds in buildbot dipy-py2.7-win32:
http://nipy.bic.berkeley.edu/builders/dipy-py2.7-win32/builds/127/steps/shell_5/logs/stdio

[omarocegueda]

And tests passed in dipy-py2.7-win32 too =D
http://nipy.bic.berkeley.edu/builders/dipy-py2.7-win32/builds/127/steps/shell_6/logs/stdio

[MrBago]

This looks good, out of curiosity when do we expect npy_math to not have npy_rint?

[omarocegueda]

Honestly, I don't know, I may have been too "paranoid", like the codility.com guys say: "Assume nothing, trust no one" ;-) . Maybe it's not necessary, I'll check as soon as the buildbots get back online =)

[omarocegueda]

I was reading a bit more the numpy code and I think the npy_* versions are always available. If the native version is available, they simply decorate them with prefix 'npy_':

https://github.com/numpy/numpy/blob/a435de365a603f29bf243882644f1e26edda6e9a/numpy/core/src/npymath/npy_math.c.src#L433
here is where they call the native function:
https://github.com/numpy/numpy/blob/a435de365a603f29bf243882644f1e26edda6e9a/numpy/core/src/npymath/npy_math.c.src#L450

and if the native function is not available, then they define different versions of their own implementation with different types of arguments and return values:

https://github.com/numpy/numpy/blob/a435de365a603f29bf243882644f1e26edda6e9a/numpy/core/src/npymath/npy_math.c.src#L362

here is where they call the (generic) version for each return/parameter type:
https://github.com/numpy/numpy/blob/a435de365a603f29bf243882644f1e26edda6e9a/numpy/core/src/npymath/npy_math.c.src#L375

so, in theory, it should be possible to simply call the npy_* version without adding any extra code in dpy_math.h (just including "numpy/npy_math.h" should be enough). Unfortunately the win32 buildbots are still offline... I'll try this as soon as they are back online.

[matthew-brett]

Not sure what is happening with the buildbots, but I suspect there was a
power failure, and only some of them came back up.

There's a 'storm' at the moment in Berkeley apparently. Thomas Kluyver
works in the next-door office, is at home because of the storm, but if he
goes in, he will reboot the machines. That might not be today though -
sorry to say.

[omarocegueda]

Hi!, I hope you guys are fine after the big storm!. The buildbots are working now, and we effectively can just include "numpy/npy_math.h" from "dpy_math.h" and use all the "npy_*" functions without adding any extra code. After that, the tests pass in win32:
http://nipy.bic.berkeley.edu/builders/dipy-bdist32-27/builds/160/steps/shell_8/logs/stdio
and I had no issues locally, I'm just waiting to see what Travis says...

[Garyfallidis]

Nice! Thx!