to compile on DECstation using the native compiler:
cmex pchirp2ia.c img_resample.c interp.c dst_to_src_pchirp2.c CC=cc

to compile on an HP, using the native compiler:
cmex pchirp2ia.c img_resample.c interp.c dst_to_src_pchirp2.c CFLAGS=-Aa

to compile using gcc, if gcc is present:
cmex pchirp2ia.c img_resample.c interp.c dst_to_src_pchirp2.c CC=gcc