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zhangxiaodao

银虫 (小有名气)

[求助] 根据数据和方程的形式,求方程中的参数

RT, 数据如下列, 然后方程的形式为y=a*exp[-p/(x+q)],求方程中的p和q,谢谢各位大侠,急求啊~~
x=1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
2.4
y=10363972.36
5697599.795
3269017.372
1948866.775
1202604.284
765578.5464
501320.0508
336809.4864
231640.3371
162754.7914
116618.904
85080.3473
63109.81473
47535.43773
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dbb627

荣誉版主 (著名写手)

【答案】应助回帖

★
感谢参与,应助指数 +1
zhangxiaodao(金币+20): 2011-12-20 13:52:42
xiegangmai(金币+1): 谢谢应助! 2011-12-20 23:02:49
General model:
     f(x) = a*exp(-p/(x+q))
Coefficients (with 95% confidence bounds):
       a =           1  (1, 1)
       p =         -42  (-42, -42)
       q =         1.5  (1.5, 1.5)

Goodness of fit:
  SSE: 1.767e-007
  R-square: 1
  Adjusted R-square: 1
  RMSE: 0.0001267

初值a=10000 p=-2  q=-1
The more you learn, the more you know, the more you know, and the more you forget. The more you forget, the less you know. So why bother to learn.
6楼2011-12-20 11:22:06
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715211229

木虫 (正式写手)

★ ★
臭水沟(金币+2): 谢谢交流~~ 2011-12-20 11:03:15
matlab :ctool工具箱
%%%拟合效果很差

Fit computation did not converge:
Maximum number of function evaluations exceeded. Increasing
MaxFunEvals (in fit options) may allow for a better fit, or
the current equation may not be a good model for the data.

Fit found when optimization terminated:

General model:
       f(x) = a*exp(-p/(x+q))
Coefficients (with 95% confidence bounds):
       a =       11.28  (-2.505e+004, 2.507e+004)
       p =      -7.497  (-3191, 3176)
       q =     -0.4499  (-151.6, 150.7)

Goodness of fit:
  SSE: 1.309e+014
  R-square: -0.159
  Adjusted R-square: -0.3697
  RMSE: 3.45e+006


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我是蜗牛
2楼2011-12-20 05:28:41
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zhangxiaodao

银虫 (小有名气)

送鲜花一朵
引用回帖:
楼: Originally posted by 715211229 at 2011-12-20 05:28:41:
matlab :ctool工具箱
%%%拟合效果很差

Fit computation did not converge:
Maximum number of function evaluations exceeded. Increasing
MaxFunEvals (in fit options) may allow  ...

谢谢
4楼2011-12-20 09:00:53
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715211229

木虫 (正式写手)

★
臭水沟(金币+1): 谢谢交流~~ 2011-12-20 11:03:26
你看下这个帖子,我这个可能是错误的
http://muchong.com/bbs/viewthread.php?tid=3866180
我是蜗牛
5楼2011-12-20 10:48:24
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