why do I get the wrong angle

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Sarah Alhabbas
Sarah Alhabbas 2022-6-14
评论： Torsten 2022-6-14
why do i keep getting a negatie value for angle

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回答（1 个）

David Hill
David Hill 2022-6-14
编辑：David Hill 2022-6-14
Recommend avoiding using symbolics. Seeking numerical solution, use fzero.
mo=2.5;
y=1.4;
angle=10;
fun=@(a)((2*(1+((y-1)/2)*mo^2*(sind(a)).^2))./(((y+1)*mo^2*sind(a).*cosd(a))))-tand(a-angle);
A=fzero(fun,32);
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David Hill
David Hill 2022-6-14
You could also plot and see that there are two solutions between (0 - 90).
mo=2.5;
y=1.4;
angle=10;
fun=@(a)((2*(1+((y-1)/2)*mo^2*(sind(a)).^2))./(((y+1)*mo^2*sind(a).*cosd(a))))-tand(a-angle);
x=3:.1:87;
plot(x,fun(x));
David Hill
David Hill 2022-6-14
编辑：David Hill 2022-6-14
Ran in:
When you graph the function you see solutions should be around 30 and 80. fzero requires an initial guess. 32 is not an exact solution.
mo=2.5;
y=1.4;
angle=10;
fun=@(a)((2*(1+((y-1)/2)*mo^2*(sind(a)).^2))./(((y+1)*mo^2*sind(a).*cosd(a))))-tand(a-angle);
A=fzero(fun,30)
A = 31.8506
mo=2.5;
y=1.4;
angle=10;
fun=@(a)((2*(1+((y-1)/2)*mo^2*(sind(a)).^2))./(((y+1)*mo^2*sind(a).*cosd(a))))-tand(a-angle);
A=fzero(fun,80)
A = 85.5761

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