Support single precision

[brian-team]

Support single precision

[neworderofjamie]

The next release (coming soon) will indeed be 3.2.0

…

On Tue, 4 Sep 2018 at 16:44, Marcel Stimberg ***@***.***> wrote: @tnowotny <https://github.com/tnowotny> , @neworderofjamie <https://github.com/neworderofjamie> Which version should we require for this feature? Current version.txt still says 3.1.1, but that release did not yet contain the feature. Should we require 3.1.2 or will the next release be 3.2? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#69 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGeoGr_RUWyVXFsnO-NyJL9XcyYT0LDcks5uXp_PgaJpZM4WReu1> .

[neworderofjamie]

Hah good idea - sorry for confusing the issue!

Unless you have any strong objections my plan is, in the short term, to add support for independantly setting double-precision time in GeNN and, in the longer term, I'll remove the transcendental function name mangling along with a lot of essentially legacy stuff meaning that you'll have much more control over precision.

[tnowotny]

I think this is a good plan. After phase one (introducing the independent precision control for t) we can adjust Brian2genn and finally get to benchmarking.
Remains the question about a version info functionality for GeNN ...

[neworderofjamie]

Excellent! I'll implement that ASAP so as not to hold you up. Regarding the versioning, if you want a hack you can read the PROJECT_NUMBER from doxygen/genn-doxygen.conf 😄 however we really should do it properly - would a #define work for you @mstimberg?

[mstimberg]

genn-doxygen.conf could be a stop-gap solution :) a #define wouldn't be the ideal solution for us, since we need the version before compiling anything...

[neworderofjamie]

I'll add a version.txt ASAP as well - I fear that any cunning attempt at reading a version.txt into the doxygen will break any stop gap hack involving parsing it so probably best not to do that...

[tnowotny]

I assume we will then have to do the logic in a away that has GeNN version < XXX if the version.txt does not exist and otherwise its content ... don't think it is possible to introduce retrospectively into earlier versions ...

[neworderofjamie]

@mstimberg - does genn-team/genn#206 work for you?

[mstimberg]

@neworderofjamie : yes looking good to me
@tnowotny : yes, not having it for older versions is perfectly fine

[tnowotny]

@mstimberg , once we have merged genn-team/genn#207 we should be ready to enable float32 support for brian2genn. Just needs inserting the setTimePrecision command if the GeNN used is new enough to have it.

[mstimberg]

Great, I'll take care of this tomorrow.

[mstimberg]

@tnowotny , @neworderofjamie Which version should we require for this feature? Current version.txt still says 3.1.1, but that release did not yet contain the feature. Should we require 3.1.2 or will the next release be 3.2?

[denisalevi]

When do you expect single precision to be available in the brian2genn? I guess it depends on the GeNN 3.2 release?
We will start running final benchmarks on Friday. If single precision is available by then, we would be happy to include it.

[mstimberg]

I just opened PR #72 which removes the need to wait for GeNN 3.2 -- it just raises a warning for now, we can change this into an error as soon as GeNN 3.2 is released.

[tnowotny]

being lazy I will ask and not inspect the code: What happens of one tries to use the single precision brian2genn with an older GeNN version before the setTimePrecision function was introduced? I suspect it crashes during compilation?

[mstimberg]

Yes, unfortunately it will raise a warning and then crash... Maybe it would be cleaner to say something about the GeNN version in the error message you get for the failed compilation?

[tnowotny]

on the other hand it could have crashed during compilation for many different reasons ... on second thought, I think it is fine with warning + crash as you have it for now. Once GeNN 3.2. is released we change it to an error and everything is clean.