To use hardware fpu floating point on Cortex-M4
the compile options
  	-mthumb -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -fsingle-precision-constant
or
 	-mthumb -mcpu=cortex-m4 -mfloat-abi=softfp -mfpu=fpv4-sp-d16 -fsingle-precision-constant
needs to be stated
