how to do sum of element of multiple number in matlab?

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Hello everyone.
If I have
m=[3 3 4 3 2 4 3]
c=[3 4]
then I want to calculate the sum of m(c) at the same time
I tried
b=1:m(c)
b=sum(b)
but only give me one number. I want it to be 2 numbers. How to do this?
Thanks in advance
  2 个评论
Timo Dietz
Timo Dietz 2020-11-18
Could you please explain in more detail? Does c contain the indices up to which you like to sum up m - starting always from 1? Or why do you expect two numbers as result?
Putri Basenda Tarigan
this means that for c=3, I want to sum m from 1 to 3, so it's 10. and for c=4, it's sum of m from 1 to 4, so it's 13.
then I want to achieve these two numbers to compare them in the next step

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采纳的回答

Rik
Rik 2020-11-18
b=cumsum(m);
b=b(c);
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更多回答(1 个)

Timo Dietz
Timo Dietz 2020-11-18
编辑:Timo Dietz 2020-11-18
Not sure whether I got your issue. But in case you want to summarize all members of m starting at index 1, up to each member of c (containing indices of m) individually, you can do this:
b=arrayfun(@(x) sum(m(1:x)), c)
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Rik
Rik 2020-11-18
Functions like arrayfun and cellfun tend to be slower than using a for loop. The exception appears to be the legacy calls of cellfun (so those with the char input, instead of a function handle).

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