# 2*atan(x)
# x	y1
-20.0	-3.0416758621459077
-19.0	-3.0364265303679097
-18.0	-3.0305956430983594
-17.0	-3.024081008158348
-16.0	-3.0167550335978786
-15.0	-3.0084563260381456
-14.0	-2.9989777240192126
-13.0	-2.9880488710502373
-12.0	-2.9753101898129106
-11.0	-2.960272879188303
-10.0	-2.9422553486074694
-9.0	-2.920278211242002
-8.0	-2.89288266449627
-7.0	-2.8577985443814655
-6.0	-2.8112952987605397
-5.0	-2.746801533890032
-4.0	-2.651635327336065
-3.0	-2.498091544796509
-2.0	-2.214297435588181
-1.0	-1.5707963267948966
0.0	0.0
1.0	1.5707963267948966
2.0	2.214297435588181
3.0	2.498091544796509
4.0	2.651635327336065
5.0000000000000036	2.746801533890032
6.0	2.8112952987605397
7.0	2.8577985443814655
8.0	2.89288266449627
9.0	2.920278211242002
10.0	2.9422553486074694
10.999999999999996	2.960272879188303
12.0	2.9753101898129106
13.0	2.9880488710502373
14.0	2.9989777240192126
15.0	3.0084563260381456
16.0	3.0167550335978786
17.0	3.024081008158348
18.0	3.0305956430983594
19.0	3.0364265303679097