Undefined function or method 'Ei' for input arguments of type 'sym'

syms x1 x2 x3 theta g开发者_如何学Pythonamma beta rho miu sigma;
f=-(exp(i*x1)-1)*Ei(1, x2)/(i*x1);

Undefined function or method 'Ei' for input arguments of type 'sym'

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the function Ei does either not exist or is not in your matlab path.

Edit: this function seems to be new in matlab 2011b, so if you are using an older version of matlab, the function won't be there -> error.

Edit2: do you have the Symbolic Math Toolbox installed?