Error while using the FreeRTOS Demo for LPC2106

Hello,

I was testing the WinARM samples.
I was able to compile the FreeRTOS demo.

After building successfully, I added following lines to main.c file of
\FreeRTOS_4_0_2\Demo\ARM7_LPC2106_GCC\

float f;
f = atof("1.12");

And now make does give following error:

c:/winarm/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/interwork 
\libc.a(
mallocr.o): In function `_malloc_r':
mallocr.c:(.text+0x40c): undefined reference to `_sbrk_r'
mallocr.c:(.text+0x4b4): undefined reference to `_sbrk_r'
c:/winarm/bin/../lib/gcc/arm-elf/4.1.1/../../../../arm-elf/lib/interwork 
\libc.a(
freer.o): In function `_malloc_trim_r':
mallocr.c:(.text+0x48): undefined reference to `_sbrk_r'
mallocr.c:(.text+0x64): undefined reference to `_sbrk_r'
mallocr.c:(.text+0x84): undefined reference to `_sbrk_r'
collect2: ld returned 1 exit status
make: *** [rtosdemo.elf] Error 1

I have to use the atof function in my code, so I was testing it.

What should I do to remove this error.

Thanks,

Rushikesh Shingnapurkar