how to make sum of (for loop)
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I need for loop or any method to calculat next sum
- m=1:n
- a+2(cos(b))
- a+2(cos(b)+cos(2b))
- a+2(cos(b)+cos(2b)+cos(3b))
- a+2(cos(b)+cos(2b)+.............cos(nb))
回答（3 个）
Roger Stafford
2014-6-7
编辑：Roger Stafford
2014-6-7
Assuming b is a scalar,
s = a + 2*sum(cos((1:n)*b));
An alternate formula without the long summation is:
s = a + 2*cos((n+1)*b/2)*sin(n*b/2)/sin(b/2);
David Sanchez
2014-6-9
the for loop:
a = 3; % or whatever value you have in mind
b = 2; % or whatever value you have in mind
n = 10; % or whatever value you have in mind
your_sum = 0; % initialization of summation part
for m=1:n
your_sum = your_sum + cos(m*b);
end
your_sum = a + 2*your_sum;
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2014-6-9
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