Phil, what processor are you compiling for? Or what's wrong with <math.h>? It works for me, but gcc is generating floating point assembler instructions and so it doesn't need -lm. If we do add a -lm it should be added to lib/Module.mk for the library, not in prog/sensors/Module.mk for sensors. Jean Delvare wrote: >>FYI- >> >>gcc -o prog/sensors/sensors prog/sensors/main.ro prog/sensors/chips.ro >>-Llib -lsensors >>lib/libsensors.so: undefined reference to `log' >>lib/libsensors.so: undefined reference to `exp' >>collect2: ld returned 1 exit stat > > > Looks like we need an extra "-lm" on the command line. >