Help with this Matrix summation?

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Jihun Sung
Jihun Sung 2017-11-2
评论： Star Strider 2017-11-2
Hi guys,
I am having trouble with matrix summation.
For example, let's say Y = [5 6 7; 17 18 19]. If I do sum(Y), ans = [22 24 26]. Good, this is what I want.
But when Y = [17 18 19], the sum(Y) = 54.
How can I make it so that no matter what it takes the sum of, the answer will always output a row of sums of the columns of Y? I need this because for my function, I don't know what matrix values I will get, but I will always need an output that is a row vector.
Ex. Y = [17 18 19]. ans = [17 18 19].
Thank you!

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Star Strider
Star Strider 2017-11-2
The second argument to sum is the dimension to sum across.
Example —
Y = [5 6 7; 17 18 19];
col_sum = sum(Y,1)
row_sum = sum(Y,2)
col_sum =
22 24 26
row_sum =
18
54
  2 个评论
Jihun Sung
Jihun Sung 2017-11-2
Ah, so simple!
Thank you so much.
Star Strider
Star Strider 2017-11-2
As always my pleasure!
The ‘dimension’ conventions can be a bit confusing until you get used to them.

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