This suppresses "unused variable" CMake warning when user explicilty disables
module unavailable in selected configuration

issue 2526

issue #2678

(Sometimes sample_data became bad because the buffer with its values was deallocated early).

* always use "argN" names for unnamed arguments
* honor space symbol between typename and "*", "&" symbols
* fix indent errors

On some platforms sin and cos are calculated in single precision resulting in
diversity of results.