求教matlab曲线拟合

知道x,y,z等于一数组,怎么把这三个数据拟合成一个好的公式,谢谢.
x=[1.1
1.11
1.12
1.13
1.14
1.15
1.17
1.2
1.22
1.25
1.17
1.2
1.23
1.25
1.3
1.35
1.4
1.21
1.23
1.25
1.3
1.35
1.4
1.45
1.5
1.52
1.53
1.31
1.35
1.4
1.45
1.5
1.55
1.6
1.61
1.62
]
y=[1.809847247
2.190843491
2.788783801
3.585792486
4.127817843
4.56445202
6.048663001
7.033339349
8.260960921
10.51560008
1.556466358
1.809847247
2.599244667
3.444434289
6.171532397
9.414540469
15.72195505
1.510216814
1.604132267
1.703888015
2.041943251
2.599244667
4.086520781
6.360532115
10.51560008
13.38559111
15.72195505
1.773814893
1.961446285
2.327084894
2.903234366
3.770675976
5.307510105
9.509680781
10.41039598
12.8

这种分段函数实在很难拟合。

x=[1.1
1.11
1.12
1.13
1.14
1.15
1.17
1.2
1.22
1.25
1.17
1.2
1.23
1.25
1.3
1.35
1.4
1.21
1.23
1.25
1.3
1.35
1.4
1.45
1.5
1.52
1.53
1.31
1.35
1.4
1.45
1.5
1.55
1.6
1.61
1.62
]
y=[1.809847247
2.190843491
2.788783801
3.585792486
4.127817843
4.56445202
6.048663001
7.033339349
8.260960921
10.51560008
1.556466358
1.809847247
2.599244667
3.444434289
6.171532397
9.414540469
15.72195505
1.510216814
1.604132267
1.703888015
2.041943251
2.599244667
4.086520781
6.360532115
10.51560008
13.38559111
15.72195505
1.773814893
1.961446285
2.327084894
2.903234366
3.770675976