我如何使用 fittype 函数来定义自定义方程式？

Question

如何使用 fittype 函数定义以下自定义方程？

y = a(x1^b)(x2^c)(x3^d)(x4^e)(x5^f)(x6^g).

我尝试了以下代码：

ft = fittype( 'a*(x1^b)*(x2^c)*(x3^d)*(x4^e)*(x5^f)*(x6^g)',...
'independent',{'x1','x2','x3','x4','x5','x6'},...
'dependent',{'y'},...
'coefficients',{'a','b','c','d','e','f','g'});

但是它抛出这个错误：

Expression a*(x1^b)(x2^c)(x3^d)(x4^e)(x5^f)*(x6^g) is not a valid MATLAB expression, has non-scalar coefficients, or cannot be evaluated: Not enough inputs to FITTYPE function.

Answer 1

首先，'a*(x1^b)(x2^c)(x3^d)(x4^e)(x5^f)(x6^g)' 不是有效的 MATLAB 表达式。您应该将其更改为 'a(x1.^b).(x2.^c).(x3.^d).(x4.^e).(x5.^f).*(x6.^g)'。其次，matlab处理不了那么多未知参数，短一个也行，像这样：

ft = fittype(@(a,b,c,x1,x2) a*(x1.^b).*(x2.^c), 'independent',{'x1','x2'},'dependent',{'y'},'problem',{'b','c'});

我如何使用 fittype 函数来定义自定义方程式？

How can i use fittype function to define a custom equation?

matlab

curve-fitting