Lpc2000

Hi,
I'm new to LPC2138, I'm actually modify a design who run on a dallas 
87c520 to a LPC2138 with GCC. 
I want to do this (it's run well with keil PK51 but not with GCC) :

unsigned char Tab[3];
float Resolution[8];

Resolution[1]=(float)(Tab[7]|Tab[8]*0x0100)*0.00001;

It compil well but I've got this error on the linking :
error: undefined reference to '__floatsisf'
:/cygdrive/c/ARM7/../driver.c:293: undefined reference 



Thanks for you help
Sebastien