函数问题

IBB-EUT · 发表于 2021-1-18 17:05

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三段式函数的拟合，一直提醒函数格式有误，但是苦于没有正确的示例，不知道正确的格式。
左边是想要拟合的公式，右边是代码，请指正，万分感激！

Title "Type your title here";
Parameters a,b,c,d ;
Variable x,y ;
Function
if x<a,y=b*(x/a) else if a<=x<=c,y=b else if x>c,y=b*(c/x)^d;
data;
0.1 12.2622
0.2 126.989
0.3 168.831
0.4 504.78
0.5 1660.53
0.6 3194.8
0.7 5118.09
0.8 5593.49
0.9 6354.52
1 6951.39
1.1 6057.45
1.2 5126.59
1.3 5155.45
1.4 5167.41
1.5 6408.55
1.6 6983.15
1.7 10444.6
1.8 9819.3
1.9 8233.5
2 8548.7
2.1 9723.07
2.2 6976.66
2.3 8150.64
2.4 8704.88
2.5 10920.1
2.6 11601.9
2.7 9217.56
2.8 10517.2
2.9 13225.9
3 10667.9
3.1 7870.21
3.2 6025.27
3.3 5713.58
3.4 5444.97
3.5 7526.2
3.6 11122.6
3.7 10034.6
3.8 8191.89
3.9 7777.02
4 9546.24
4.1 11494.7
4.2 11492.1
4.3 10388.3
4.4 9548.41
4.5 12450.7
4.6 18987.2
4.7 28381.8
4.8 36321.2
4.9 39182.1
5 39738
5.1 38192.9
5.2 35211.8
5.3 31235.4
5.4 27255.3
5.5 23579.2
5.6 20797.7
5.7 19082.9
5.8 17750.6
5.9 17354.2
6 18027.8
6.1 20452.5
6.2 22496.6
6.3 25224.6
6.4 27468.6
6.5 29534.9
6.6 29086.3
6.7 26879.5
6.8 23869.6
6.9 21170.5
7 18538.5
7.1 15742.2
7.2 13204.2
7.3 12671.2
7.4 11967
7.5 11079.9
7.6 10199.8
7.7 9508.26
7.8 8949.19
7.9 8586.8
8 8718.86
8.1 8936.01
8.2 9141.13
8.3 9499.2
8.4 9767.39
8.5 9876.61
8.6 9566.14
8.7 8802.23
8.8 7706.28
8.9 6755.66
9 6311.97
9.1 5814.99
9.2 5271.1
9.3 4729.66
9.4 4278.74
9.5 3900.71
9.6 3607.55
9.7 3393.22
9.8 3242.63
9.9 3136.26
10 3050.8
10.1 2970.71
10.2 2942.11
10.3 2898.5
10.4 2829.74
10.5 2732
10.6 2673.95
10.7 2618.58
10.8 2538.54
10.9 2439.27
11 2327
11.1 2207.77
11.2 2099.27
11.3 2005.83
11.4 1939.58
11.5 1868.75
11.6 1792.37
11.7 1716.14
11.8 1647.1
11.9 1592.69
12 1535.02
12.1 1487.1
12.2 1442.02
12.3 1404.55
12.4 1372.14
12.5 1339.26
12.6 1306.91
12.7 1274.2
12.8 1240.19
12.9 1205.69
13 1174.97
13.1 1143.4
13.2 1111.18
13.3 1091.32
13.4 1073.65
13.5 1063.19
13.6 1059.7
13.7 1059.07
13.8 1067.5
13.9 1079.59
14 1092.71
14.1 1107.18
14.2 1122.07
14.3 1136.8
14.4 1151.09
14.5 1164.63
14.6 1177.12
14.7 1188.84
14.8 1199.04
14.9 1207.72
15 1214.96
15.1 1220.1
15.2 1223.03
15.3 1223.68
15.4 1221.98
15.5 1218.29
15.6 1213.32
15.7 1205.84
15.8 1196.24
15.9 1184.64
16 1170.7
16.1 1154.55
16.2 1136.4
16.3 1116.58
16.4 1095.05
16.5 1072.02
16.6 1047.73
16.7 1022.4
16.8 996.294
16.9 969.694
17 944.492
17.1 919.623
17.2 921.07
17.3 921.284
17.4 920.186
17.5 917.719
17.6 913.863
17.7 908.738
17.8 902.358
17.9 894.874
18 886.424
18.1 876.931
18.2 866.692
18.3 855.953
18.4 844.501
18.5 833.049
18.6 821.271
18.7 808.993
18.8 796.315
18.9 783.336
19 770.44
19.1 757.745
19.2 745.081
19.3 732.521
19.4 720.132
19.5 707.972
19.6 696.095
19.7 684.546
19.8 673.363
19.9 662.575
20 652.206

llbnmo · 发表于 2021-1-18 18:01

帮你顶一下

shuddkk · 发表于 2021-1-19 11:26

Title "Type your title here";
Parameters a,b,c,d ;
Variable x,y ;
StartProgram [Basic];
Sub MainModel
Dim i as integer
Dim as double tx, ty
for i = 0 to DataLength - 1
   tx = x(i)
   if tx < a then
      ty = b*(x(i)/a)
   elseif tx > c then
      ty = b*(c/x(i))^d
   else
      ty = b
   end if
   y(i) = ty
next
End Sub
EndProgram;
data;
0.1 12.2622
0.2 126.989
0.3 168.831
0.4 504.78
0.5 1660.53
....

IBB-EUT · 发表于 2021-1-19 14:15

shuddkk 发表于 2021-1-19 11:26+ ^1 O9 ~5 O6 x0 r" H' z+ [
Title "Type your title here";
) {* f [& [" j" o/ D7 jParameters a,b,c,d ;
& ^6 O% z7 Z5 v# }4 k( eVariable x,y ;

谢谢大佬，

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