# How can I fix this error?

1 view (last 30 days)
Andrew Williams on 5 Sep 2018
Answered: Naman Chaturvedi on 10 Sep 2018
"Unable to perform assignment because the left and right sides have a different number of elements."
I'm trying to write a code that will approximate sin(0.3*pi) using a Taylor series expansion to 20 terms. What I currently have is:
a=0; x=0.3*pi; n=0; f(1)=0; y=sin(a);
for i=[1:20]
f(i+1)=(y*((x-a)^n))/factorial(n) y=diff(y); n=n+1;
end
Any advice or ways to help fix this problem would be greatly appreciated, I'm a novice still at using MATLAB.
Andrew Williams on 5 Sep 2018
or better yet, how can i get my program to take successive derivatives in a loop?

Naman Chaturvedi on 10 Sep 2018
You are getting the error because after performing 'y=diff(y)', y becomes '[]' which makes the RHS '[]' as well. The correct code to find the expansion would be:-
n = 20;
x = pi/3;
y = zeros(1,20);
for i = 0:n
y(i+1) = (-1)^i*x^(2*i+1)/factorial(2*i+1);
end
approx_sinx=sum(y); %Approximated value

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