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各位大神,我在用matlab中的cftool拟合非线性函数,得到的cfit如何进行函数操作,求导等。
PS 我试了提取出各个系数,构造函数,然后对构造的函数进行求导,但结果不理想,得到的函数g 在相同的x值处 函数值很不好,是exp的一个表示,为
g(0)
ans =
(81237295002235*exp(-546461714598735789728624069099536/6544490893783104415829273208081))/140737488355328 + (2495506857451569*exp(-22784005895725160164421051430121/339550163399717490602339615134096))/140737488355328 + (1158821406772579*exp(-124115814564550127768460048600676/23029478501256146398011601513041))/281474976710656 + (2946948027047363*exp(-1357341483970986610734701600625/415545017388687786102707772649))/562949953421312
而f
>> f(0)
ans =
16.799
下面是cfit函数的表示
f =
General model Gauss5:
f(x) =
a1*exp(-((x-b1)/c1)^2) + a2*exp(-((x-b2)/c2)^2) +
a3*exp(-((x-b3)/c3)^2) + a4*exp(-((x-b4)/c4)^2) +
a5*exp(-((x-b5)/c5)^2)
Coefficients (with 95% confidence bounds):
a1 = 5.235
b1 = 115.9
c1 = 64.12
a2 = 0
b2 = 221.1
c2 = 1.222
a3 = 17.73 (15.58, 19.88)
b3 = 135.7 (37.03, 234.3)
c3 = 523.7 (307.9, 739.5)
a4 = 0.5772 (0.1464, 1.008)
b4 = 332.2 (311.5, 352.9)
c4 = 36.35 (1.694, 71.02)
a5 = 4.117 (2.648, 5.586)
b5 = 1267 (939, 1594)
c5 = 545.6 (-342.1, 1433)
>> diff(f)
Error using diff
Function 'diff' is not supported for class 'cfit'.
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