cosine estimate taylor series

Question

Elena 2022-2-22

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1655525-cosine-estimate-taylor-series

评论： KSSV 2022-2-22

sos, trying to fix in 30 min, not sure what is going wrong, im getiing 1.6985 e 5 and answer should be 0.6916.

function res = cosineEstimate(ang, k) 
ang = '045-00-00'
k = 2
%DMS to degrees
angSplit = strsplit(ang, '-')
firstCell = angSplit(1)
angForm = str2double(firstCell)
%degree to rad
rad = (angForm/180)*pi;
r = 0;
for n = 1:k;
    
    e = 2*n
    f= factorial(e)
    m = (-1)^(n)
    
    r = r + m*(angForm^e)/f
    res = r
end
end  

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Answer 1

KSSV 2022-2-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1655525-cosine-estimate-taylor-series#answer_901705

编辑：KSSV 2022-2-22

在 MATLAB Online 中打开

x = 45*pi/180 ; 
n = 10 ;
thesum = 0 ;
for i = 0:n
    thesum = thesum+(-1)^i*x^(2*i)/factorial(2*i) ;
end
[cos(x) thesum]
ans = 1×2
    0.7071    0.7071

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KSSV 2022-2-22

在 MATLAB Online 中打开

cos(pi/4)
ans = 0.7071

How it is 0.6916? Are you targetting different angle? If not reduce the value of n and see.

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Answer 2

Sulaymon Eshkabilov 2022-2-22

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1655525-cosine-estimate-taylor-series#answer_901710

在 MATLAB Online 中打开

Here is the corrected code:

ang = '045-00-00';
k = 2;
res = cosineEstimate(ang, k) 
res = -0.6169
function res = cosineEstimate(ang, k) 
%DMS to degrees
angSplit = strsplit(ang, '-');
firstCell = angSplit(1);
angForm = str2double(firstCell);
%degree to rad
RAD = (angForm/180)*pi;
res= 0;
for n = 1:k
    res = res + ((-1) .^ (k-1) .* RAD .^ k) ./ factorial(k);
end
end  