gmt-fork/test/greenspline/mag_obs_1990.d

-79.27	43.79	59691.5
1.47	43.62	39408.0
44.80	41.72	37784.5
14.25	40.87	36311.0
-9.15	38.72	37522.0
-6.20	36.47	35432.5
139.75	35.69	34410.5
121.43	31.22	33744.0
114.18	22.30	22447.5
72.82	18.90	14605.5
120.98	14.59	11112.0
57.55	-19.43	-32985.0
-43.17	-22.23	-5905.0
10.45	59.92	47016.0
30.48	59.69	47064.0
60.63	56.84	50825.0
12.58	55.69	44793.0
8.15	53.54	44183.0
13.07	52.39	43013.5
104.27	52.27	57722.0
-10.25	51.94	45116.5
0.0	51.49	43798.5
2.50	48.82	42119.5
11.62	48.15	41011.0
13.85	44.87	38899.5