# How do I write the function to derive an nth taylor polynomial?

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James T on 12 Sep 2017
Commented: James T on 13 Sep 2017
function y = nthTaylorPolyExp( n, x )
%y = nthTaylorPolyExp( n, x )is a function that returns 3rd Taylor polynomial of exponential function at x=0.
% n is an input argument, which indicates the degree of Taylor
% polynomial.
% x is an input argument
% y is output.
y=zeros('like',x);
% ============= YOUR CODE HERE ==============
% Instructions: Return nth Taylor polynomial of exponential function at x=0.
% You can use built in function factorial(n) to return n!,
% and use for loop to get the sum.
for i = 0:n
% y = y + (-1)^i * (x.^(2 * i)) / factorial(2 * i); is my version, but its incorrect.
end
% ===========================================
end

James Tursa on 12 Sep 2017
You are using the series expansion for cos( ), not the series expansion for exp( ). You need to replace the terms you are using with the terms that match the series expansion for exp( ).
James T on 13 Sep 2017
for i = 0:n
y = y + (x.^i)./factorial(i);
end
%Thank you