Error lsqcurvefit using Function value and YDATA sizes are not equal.

ydata = [4.83 3.87 2.54 2.08 1.82 1.8 1.76 1.74];

xdata = [5 10 20 30 45 60 90 120];

fun2 = @(x,xdata)((42*exp((13/7)*x(1)*xdata))-140)/(10+(10* exp((13/7)*x(1)*xdata)));

x0 = [-1,1];

x = lsqcurvefit(fun2,x0,xdata,ydata)

I got the error message:

Error using lsqcurvefit (line 262)

Function value and YDATA sizes are not equal.

Error in dimethyl_kinetics2 (line 43)

x = lsqcurvefit(fun2,x0,xdata,ydata)

size(ydata)

size(fun2(x0,xdata))

ans =

1 8

ans =

1 1

I get that they need to be the same. But how do I do that?

Thanks a lot.

Answer 1

[Star Strider]

You need to do element-wise division:

fun2 = @(x,xdata)((42*exp((13/7)*x(1)*xdata))-140)./(10+(10* exp((13/7)*x(1)*xdata)));
                                                  ↑

With that change, your code works.

[Titas Deb]

Thanks so much. It works now.

[Star Strider]

As always, my pleasure!