On a Pentium 4 system, does the switch -mfpmath=sse cause the compiler to generate code using SSE2 instructions for calculations involving doubles? Note: I've also specified -march=pentium4 -mcpu=pentium4. ..Scott -- Scott Robert Ladd Coyote Gulch Productions, http://www.coyotegulch.com No ads -- just very free (and somewhat unusual) code.