Question

Hello! i need help with a problem in this textbook, Essential MATLAB, 6th edition. Question 8.11:

Use the Taylor Series,

cosx=1- (x²/2!)+(x⁴/4!)-(x⁶/6!)+.........

To write a program to compute cosx correct to 4 decimal places )x is in radians). see how many terms are needed to get 4 figure agreement with the MATLAB function cos. Dont make x too large; that could cause rounding errors.

I can get an out put correct up to about only 10 radians, but then it becomes way off, This is what i have:

function cosx = cosx(x)
i=2;
a=1;
while a>0.001
a=((x^i)/(factorial(i)))*(-1);
i=i+2;

end
a=a+1
end

Thank you!

Answer 1

CODE:

function a = cosx(x)
    i = 0;
    a = 0;
    while abs(a - cos(x)) > 0.0001
        a = a + (x^i/factorial(i))*(-1)^(i/2);
        i = i + 2;
    end
end

SAMPLE OUTPUT:

FOR ANY HELP JUST DROP A COMMENT