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matlabtrigonometrytaylor-series

Taylor series for cos(x) in matlab

I have a simple question. I want to write Taylor series expansion for cos(x). And I wrote that codes

x=input('Please input an angle in degrees: ');
cosx=1;
for i=1:1:x
addterm = (-1)^i*(x.^(2*i))/factorial(2*i);
cosx = cosx + addterm;
end
 a=['The value of cosine of ',num2str(x),' degrees is ', num2str(cosx)];
 disp(a)

But that code did not give true result.Why?

Solution

  • The Taylor series you use needs x to be expressed in radians. After the input multiply x by π/180 to convert degrees to radians. Also you need to have many iterations, not just x. Try for i=1:1:10 because factorial grows very fast.