Attempting to have a series for sin stop summing when the precision is correct

Question

Steven Manz 2019-10-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/485958-attempting-to-have-a-series-for-sin-stop-summing-when-the-precision-is-correct

关闭： MATLAB Answer Bot 2021-8-20

p = 0;
Pn = sinser(p,x);
 
figure(3)
plot(x,sin(x),'-k')
hold on
plot(x,Pn)
axis([0 100 -2 2])
title('Sine Curve Series')
xlabel('x')
ylabel('y')
legend('Sin(x)','P')
hold off
function [p,x] = sinser(p,x)
ssx = 1000000*p;
sinx = 1000000*sin(x);
floor1 = floor(ssx);
floor2  = floor(sinx);
 
        if floor1 ~= floor2
    b = 1;
        else
    b = 0;
        end
 
k = 0;
    while b == 1
        p = p + (((-1)^k*(x.^(2*k+1)))/(factorial(2*k+1)));
        k = k + 1;
    end
end

For some reason, MatLab is stating that Pn = 0. I am not sure why. I am hoping for Pn to equal some sort of summation that follows the sine curve. Ultimately it should be a 1x1001 matrix, but it is giving me a scalar value. Any help is appreciated.

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Answer 1

James Tursa 2019-10-17

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/485958-attempting-to-have-a-series-for-sin-stop-summing-when-the-precision-is-correct#answer_396899

Inside the sinser function, you never set p to a vector ... it is always just a scalar. If you want to return all of those intermediate values of p, then you need to redo your logic to save them in a vector (e.g., using p(k) and p(k+1) etc inside the function as appropriate).