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help please why ??

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ahmad qadan
ahmad qadan 2018-2-28
评论： ahmad qadan 2018-2-28
A = [ 1 3 2 6 ; 5 7 7 0 ; -2 6 -2 1 ] ;
j = sum(A(1))
j= 1 why ???

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采纳的回答

Jim Riggs
Jim Riggs 2018-2-28
the statement
sum(A(1))
is summing only the first element in A, which is 1.
If you want to sum the first row, it should be
sum(A(1,:))
and if you want to sum the first column, it is
sum (A(:,1))
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Jim Riggs
Jim Riggs 2018-2-28
The matrix A is:
1 3 2 6
5 7 7 0
-2 6 -2 1
The first element in A is A(1) which is 1. So the statement
sum(A(1))
is the same as
sum(1)
and has a value of 1.
ahmad qadan
ahmad qadan 2018-2-28
oooohhh ok thx a lot

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更多回答（1 个）

elham kreem
elham kreem 2018-2-28
WHAT are you want? IF YOU want to sum all the values then use Sum (A) BUt you sum the first element only. IF you help this answer then except to it.
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ahmad qadan
ahmad qadan 2018-2-28
why j = 1 ,, if the sum first element 1+1 = 2

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