Sum variables from three in three, after summing compute an equation and organize all data into a new column?

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rpid 2019-1-26

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关闭： MATLAB Answer Bot 2021-8-20

How can I sum variables from three in three and put these same sums in another column? I thought in splitting in two "for" conditions as shown below.

x=data(:,1);
i=1;
j=1;
for i=1:length(data)
    for j=1:3
        x(i)=1;
        x(i+1)=2^2;
        x(i+2)=3^3;
        h=x(i)+x(i+1)+x(i+2);
        i=i+1;
    end
    j=j+3;
end

Can anyone help me, please? Thank you.

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madhan ravi 2019-1-26

编辑：madhan ravi 2019-1-26

Urgent

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Answer 1

Steven Lord 2019-1-27

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/441627-sum-variables-from-three-in-three-after-summing-compute-an-equation-and-organize-all-data-into-a-ne#answer_358178

在 MATLAB Online 中打开

x=data(:,1);
i=1;
j=1;
for i=1:length(data)
    for j=1:3
        x(i)=1;
        x(i+1)=2^2;
        x(i+2)=3^3;
        h=x(i)+x(i+1)+x(i+2);
        i=i+1;
    end
    j=j+3;
end

The line "j=j+3;" at the end of the body of your "for i" loop does increment j ... for the remainder of that iteration over i. As soon as MATLAB moves to the next iteration of the "for i" loop, it starts a loop that assigns 1, 2, and 3 in turn to j. This throws away the value that was previously in j (which was not actually used in the for loop over j.)

Perhaps what you want is to have i jump by steps of 3? Look at the documentation for the colon function or the : operator for examples that will show you how to do that.

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rpid 2019-1-27

在 MATLAB Online 中打开

Thanks for your attention. I did it and I got another results, but the code is still not working as it should.

These are the values I need to reproduce.

i, j	x	y	h=sum_x	    sum_y
64	2	-	    -
9	55	-	    -
17	47	90	    104
40	26	-	    -
32	34	-	    -
41	23	113	    83
49	15	-	    -
8	58	-	    -
64	2	121	    75
9	55	-	    -
17	47	-	    -
40	26	66	    128
32	34	-	    -
41	23	-	    -
49	15	122	    72
n	...	...	-	    -

The code now, with your help:

x=data(:,1);
n=length(data);
i=1;
j=1;
for j=1:n
    for i=1:3
        x(i);
        x(i+1);
        x(i+2);
        h=x(i)+x(i+1)+x(i+2);
        i=i+1;
    end
    j=1:3:n;
end