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

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murat
murat 2014 年 2 月 23 日
回答済み: Walter Roberson 2014 年 2 月 23 日
why "symsum(sin(k*pi)*k,0,n)" not equal zero?

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回答 (3 件)

Walter Roberson
Walter Roberson 2014 年 2 月 23 日
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 年 2 月 23 日
What is n? For e.g. n=0.5 the result is not surprising.
Paul
Paul 2014 年 2 月 23 日
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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