Here is a list of all functions with links to the files they belong to:

radians_from_degrees() : plm_math.h
ramp_filter() : ramp_filter.cxx, ramp_filter.h
rasterize_slice() : rasterize_slice.cxx, rasterize_slice.h
raw_load() : proj_image.cxx
raw_pointset_from_itk_float_pointset() : itk_pointset.cxx, itk_pointset.h
raw_save() : proj_image.cxx
ray_trace_exact() : ray_trace.h, ray_trace_exact.cxx, ray_trace_exact_legacy.cxx
ray_trace_exact_init() : ray_trace_exact.cxx, ray_trace_exact_legacy.cxx
ray_trace_exact_init_loopvars() : ray_trace_exact.cxx, ray_trace_exact_legacy.cxx
ray_trace_probe() : ray_trace_probe.cxx, ray_trace_probe.h
ray_trace_uniform() : ray_trace.h, ray_trace_uniform.cxx
read_mha() : mha_io.cxx, mha_io.h
read_mha_internal() : mha_io.cxx
regularize_string() : string_util.cxx, string_util.h
regularize_string_callback() : string_util.cxx
remove_old_edges() : rasterize_slice.cxx
render_skin() : rtog_io.cxx
render_slice() : rtog_io.cxx
resample_image() : itk_resample.cxx, itk_resample.h
rpl_callback_accum() : rpl_volume.cxx
rpl_callback_sample() : rpl_volume.cxx
rpl_ray_trace_callback_ct_density() : rpl_volume.cxx
rpl_ray_trace_callback_ct_HU() : rpl_volume.cxx
rpl_ray_trace_callback_PrSTPR() : rpl_volume.cxx
rpl_ray_trace_callback_PrSTPR_XiO_MGH() : rpl_volume.cxx
rpl_ray_trace_callback_range_length() : rpl_volume.cxx
rpl_ray_trace_callback_RSP() : rpl_volume.cxx
rt_study_warp() : rt_study_warp.cxx, rt_study_warp.h
run_marching_squares() : cxt_extract.cxx