cc -o c4.5 c4.5.o besttree.o build.o info.o discr.o contin.o subset.o prune.o stats.o st-thresh.o classify.o confmat.o sort.o getnames.o getdata.o trees.o getopt.o header.o -lm
besttree.o(.text+0x219): In function `FormTarget':
: undefined reference to `cfree'
st-thresh.o(.text+0x5f7): In function `SoftenThresh':
: undefined reference to `cfree'
st-thresh.o(.text+0x605): In function `SoftenThresh':
: undefined reference to `cfree'
st-thresh.o(.text+0x613): In function `SoftenThresh':
: undefined reference to `cfree'
st-thresh.o(.text+0x622): In function `SoftenThresh':
: undefined reference to `cfree'
trees.o(.text+0x1022): more undefined references to `cfree' follow
gmake: *** [c4.5] Error 1