Displaying a more precise answer when using diff()

2016 5 1
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更新时间：2016 5 1
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Hi guys, I'm doing this in MATLAB
syms x
f = (cos(cos(cos(cos(cos(cos(cos(cos(cos(cos(cos(cos(cos(cos(cos(cos(x)))))))))))))))));
c = sym('1');
diff(c)
And it gives me ans = 0. But I know the answer is not 0. How can I get a more exact answer? Specifically the answer to this derivative is 0.00178818.
Thank you!

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Roger Stafford
Roger Stafford 2016-5-1

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In your code you have asked for the derivative of the constant 1, and of course its derivative will be zero. You need to find the expression for the derivative of f with respect to x and only then evaluate it for x = 1. That is, do diff(f,x) first, then find its numerical value at x = 1.

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