why "symsum(si​n(k*pi)*k,​0,n)" not equal zero

2014 2 23
3 个回答
更新时间：2014 2 23
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回答（3 个）

Walter Roberson
Walter Roberson 2014-2-23

1 个投票

symsum(sin(k*sym('pi'))*k,0,n)
Remember, "pi" in MATLAB is only a numeric approximation to the transcendental number; you need to use the transcendental number rather than the numeric approximation.
Jan
Jan 2014-2-23

0 个投票

What is n? For e.g. n=0.5 the result is not surprising.
Paul
Paul 2014-2-23

0 个投票

I don't think Matlab recognizes that sin(pi)= 0, therefore it cant simplify further sin(pi*n)*(n/2 + 1/4). Just type sin(pi) and you will see you won't get 0. sind(180) does give 0 but sind doesn't support symbolic variables.

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