whitecat198
2011-09-07, 09:08
小弟想使用lsqcurvefit求y=(x/a)^(1/b)+c中的abc三个参数，使用以下方法计算：
m函数：
function y=myfun(a,x)
y=(x/a(1))^(1/a(2))+a(3);
程序：
>> x=[0 5.555556 20 40 60 80 100 120 140 160 180 200];
y=[0.36036 0.61982 0.918919 1.16036 1.340541 1.506306 1.654054 1.783784 1.913514 2.025225 2.140541 2.255856];
x0=[1,1,1];
[x,resnorm]=lsqcurvefit(@myfun,x0,x,y)
程序提示出错：
??? Error using ==> mpower
Matrix must be square.
Error in ==> myfun at 2
F=(x/a(1))^(1/a(2))+a(3);
Error in ==> lsqcurvefit at 209
initVals.F = feval(funfcn_x_xdata{3},xCurrent,XDATA,varargin{:});
Caused by:
Failure in initial user-supplied objective function evaluation. LSQCURVEFIT cannot continue
希望好心人帮忙看看，程序错在什么地方或则有其他什么方法可以计算，谢谢
m函数：
function y=myfun(a,x)
y=(x/a(1))^(1/a(2))+a(3);
程序：
>> x=[0 5.555556 20 40 60 80 100 120 140 160 180 200];
y=[0.36036 0.61982 0.918919 1.16036 1.340541 1.506306 1.654054 1.783784 1.913514 2.025225 2.140541 2.255856];
x0=[1,1,1];
[x,resnorm]=lsqcurvefit(@myfun,x0,x,y)
程序提示出错：
??? Error using ==> mpower
Matrix must be square.
Error in ==> myfun at 2
F=(x/a(1))^(1/a(2))+a(3);
Error in ==> lsqcurvefit at 209
initVals.F = feval(funfcn_x_xdata{3},xCurrent,XDATA,varargin{:});
Caused by:
Failure in initial user-supplied objective function evaluation. LSQCURVEFIT cannot continue
希望好心人帮忙看看，程序错在什么地方或则有其他什么方法可以计算，谢谢