Trying to get my output to be 22 decimal places

Question

Griffin Murphy 2021-12-3

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1602435-trying-to-get-my-output-to-be-22-decimal-places

评论： John D'Errico 2021-12-3

%Murphy Griffin
%ERG280-01
%December 3, 2021
function out=my_sin(x)
xrad=x*pi/180;
sign=1;
n=1;
total=0;
fact=1;
while abs(total-sin(xrad))>=10^(-22)
    if n>200
        break
    end
    total=total+(sign*((xrad^n)/(factorial(fact))));
    fact=fact+2;
    sign=sign*(-1);
    n=n+2;   
end
out=total;
end

I need the output of the fuction to be 22 decimal places but I cant use

digits(22)

vpa(my_sin(73))

to get to 22 decimal places. It needs to occur when I get my answer after inputting my_sin(73)

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Matt J 2021-12-3

It needs to occur when I get my answer after inputting my_sin(73)

What's the difference?

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Answer 1

David Hill 2021-12-3

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1602435-trying-to-get-my-output-to-be-22-decimal-places#answer_847010

在 MATLAB Online 中打开

You cannot use floating point if you want 22 decimal places of accuracy, you must use symbolic.

function total=my_sin(x)
digits(22);
x=sym(num2str(x));
xrad=x*pi/180;
sign=1;
n=1;
total=sym(0);
fact=sym(1);
while abs(total-sin(xrad))>=1e-22
    if n>200
        break
    end
    total=total+(sign*((xrad^n)/(factorial(fact))));
    fact=fact+2;
    sign=sign*(-1);
    n=n+2;   
end
total=vpa(total);
end