closest_point2d_on_segment_ratio closest_point3dz_on_segment_ratio closest_point_on_segment_sphere datum_get_point2d datum_get_point2d_p datum_get_point3dz datum_get_point3dz_p datum_get_point4d datum_point_eq datum_transform ensure_has_M_gs ensure_has_not_M_gs ensure_has_not_Z ensure_has_not_Z_gs ensure_has_Z ensure_has_Z_gs ensure_non_empty ensure_not_geodetic ensure_not_geodetic_gs ensure_point_type ensure_same_dimensionality ensure_same_dimensionality_gs ensure_same_dimensionality_tpoint_gs ensure_same_geodetic ensure_same_geodetic_gs ensure_same_spatial_dimensionality ensure_same_spatial_dimensionality_stbox_gs ensure_same_srid ensure_same_srid_stbox ensure_same_srid_stbox_gs ensure_same_srid_tpoint_stbox ensure_spatial_validity fetch_fcinfo geo_serialize geo_set_precision geog_bearing geog_distance geography_interpolate_point4d geom_bearing geom_distance2d geom_distance3d geopoint_collinear geopoint_line geopoint_lwline geoseg_interpolate_point geoseg_locate_point get_distance_fn get_pt_distance_fn gs_get_point2d_p gs_get_point3dz_p interpolate_point4d_sphere lwpointarr_make_trajectory point_make pt_distance2d pt_distance3d spheroid_init store_fcinfo tgeogpoint_to_tgeompoint tgeogpointinst_to_tgeompointinst tgeogpoints_to_tgeompoints tgeogpointseq_intersection tgeogpointseq_to_tgeompointseq tgeompoint_to_tgeogpoint tgeompoint_twcentroid tgeompointseq_intersection tgeompointseq_min_bearing_at_timestamp tpoint_at_geometry tpoint_at_stbox tpoint_at_stbox_internal tpoint_azimuth tpoint_cumulative_length tpoint_get_coord_internal tpoint_get_x tpoint_get_y tpoint_get_z tpoint_length tpoint_minus_geometry tpoint_minus_stbox tpoint_restrict_geometry_internal tpoint_set_precision tpoint_set_srid tpoint_set_srid_internal tpoint_speed tpoint_srid tpoint_srid_internal tpoint_trajectory tpoint_trajectory_external tpoint_trajectory_free tpoint_trajectory_internal tpoint_twcentroid_internal tpointinst_srid tpointinst_transform tpointinstset_make_simple1 tpointinstset_srid tpointinstset_trajectory tpointinstset_twcentroid tpointseq_at_geometry tpointseq_interperiods tpointseq_intersection_value tpointseq_make_simple1 tpointseq_make_trajectory tpointseq_srid tpointseq_trajectory tpointseq_trajectory_copy tpointseq_twcentroid tpointseqset_srid tpointseqset_trajectory tpointseqset_twcentroid

datum_transform() Datum datum_transform ( Datum  value, Datum  srid  ) Call the PostGIS transform function. We need to use the fcinfo cached in the external functions stbox_transform and tpoint_transform