how I use function F = myfun1(x,xdata) F= @(x,xdata)​x(1).*exp(​x(2).*xdat​a);

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MUMATZ QURESHI
MUMATZ QURESHI 2019-3-27
回答： Rajanya 2025-7-1
function F = myfun1(x,xdata)
F= @(x,xdata)x(1).*exp(x(2).*xdata);
% Assume you determined xdata and ydata experimentally
xdata = [0.9 1.5 13.8 19.8 24.1 28.2 35.2 60.3 74.6 81.3];
ydata = [455.2 428.6 124.1 67.3 43.2 28.1 13.1 -0.4 -1.3 -1.5];
x0 = [100, -1]; % Starting guess
x = lsqcurvefit(@myfun1,x0,xdata,ydata);
Error: Failure in initial objective function evaluation. LSQCURVEFIT cannot continue.

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回答（1 个）

Rajanya
Rajanya 2025-7-1
Ran in:
Hi @MUMATZ QURESHI,
The following line makes 'F' a function handle to an anonymous function-
F= @(x,xdata)x(1).*exp(x(2).*xdata);
However, 'lsqcurvefit' expects a vector of values (see here), and hence it cannot continue.
Changing the function definition of 'myfun1' to the following returns a vector of predicted values-
function F = myfun1(x,xdata)
F = x(1).*exp(x(2).*xdata);
end
Then, the error is resolved.
xdata = [0.9 1.5 13.8 19.8 24.1 28.2 35.2 60.3 74.6 81.3];
ydata = [455.2 428.6 124.1 67.3 43.2 28.1 13.1 -0.4 -1.3 -1.5];
x0 = [100, -1]; % Starting guess
x = lsqcurvefit(@myfun1,x0,xdata,ydata);
Local minimum possible. lsqcurvefit stopped because the final change in the sum of squares relative to its initial value is less than the value of the function tolerance.
x
x = 1×2
498.8309 -0.1013
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To learn more about anonymous functions and how they are used, you can refer to its documentation by executing the following command from MATLAB Command Window-
doc Anonymous Functions
Thanks!

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