However, defining GLM\_FORCE\_UNRESTRICTED\_GENTYPE is not compatible with GLM\_FORCE\_SWIZZLE and will generate a compilation error if both are defined at the same time.
### <aname="section3_9"></a> 3.9. GLM\_FORCE\_SINGLE\_ONLY: Removed explicit 64-bits floating point types
Some platforms (Dreamcast) doesn't support double precision floating point values. To compile on such platforms, GCC has the --m4-single-only build argument. When defining GLM\_FORCE\_SINGLE\_ONLY before including GLM headers, GLM releases the requirement of double precision floating point values support. Effectivement, all the float64 types are no longer defined and double behaves like float.