Question

matlab进行复杂函数的拟合

function F=myfun(x,xdata)
F=x(1)-((xdata-x(2))^x(3))/x(4)

xdata=[211.0 203.0 181.0 198.0 308.0 279.0 282.0 300.0 300.0 395.0 397.5 420.0 520.0 500.0];

ydata=[0.539426329 0.549146493 0.55177182 0.552454165 0.531121066 0.543953678 0.445927983 0.44839669 0.54054826 0.479326121 0.480062915 0.475330964 0.432280448 0.427907858]

x0=[0.85 450 5 150];

[x,resnorm]=lsqcurvefit(@myfun,x0,xdata,ydata)

提示的错误是
??? Error using ==> optim\private\lsqncommon at 98
LSQCURVEFIT cannot continue because user supplied objective function failed with the following error:
Error using ==> mpower
Matrix must be square.

Error in ==> lsqcurvefit at 182
[x,Resnorm,FVAL,EXITFLAG,OUTPUT,LAMBDA,JACOB] = ...

Answer 1

这个很简单是你的函数中乘方忘记加点了，系统当做矩阵了
function F=myfun(x,xdata)
F=x(1)-((xdata-x(2))^x(3))/x(4)改成
function F=myfun(x,xdata)
F=x(1)-((xdata-x(2)).^x(3))/x(4)
希望解决了你的问题！