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

lsqcurvefit

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.

Best Answer

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.

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MATLAB: This is the code i am getting error with x = simulannealbnd(ObjectiveFunction,X0,ydata,lb,ub). can help me to resolve it

The simulannealbnd function does not expect ydata to be passed to it. You might need

ObjectiveFunction = @(x)parameterized_objective(x,xdata,ydata);
   x = simulannealbnd(ObjectiveFunction,X0,lb,ub)

having changed parameterized_objective to expect ydata

MATLAB: Lsqcurvefit question (Function value and YDATA sizes are not equal.)

Hi,

Use elementwise operations to declare your function:

xdata=[1,5,10,20,50];
ydata=[0.3, 1.6, 2.8, 4.6, 7.6];
fun=@(x,xdata)x(1).*1-x(1).*(1-exp(((-1).*x(2)).*xdata))./(x(2).*xdata);
x0=[10,5];
x=lsqcurvefit(fun,x0,xdata,ydata);

This version works.

Best regards

Stephan

Best Answer

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MATLAB: Lsqcurvefit question (Function value and YDATA sizes are not equal.)

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MATLAB: This is the code i am getting error with x = simulannealbnd(ObjectiveFunction,X0,ydata,lb,ub). can help me to resolve it