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

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.

[madhan ravi]

Urgent

Answer 1

[Steven Lord]

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.

[rpid]

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
1	64	2	-	    -
2	9	55	-	    -
3	17	47	90	    104
4	40	26	-	    -
5	32	34	-	    -
6	41	23	113	    83
7	49	15	-	    -
8	8	58	-	    -
9	64	2	121	    75
10	9	55	-	    -
11	17	47	-	    -
12	40	26	66	    128
13	32	34	-	    -
14	41	23	-	    -
15	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

The h value returns just one number ow and I need a sequence as presented in h=sum_x. Can you help me, please? Thks!!!

Answer 2

[Kevin Phung]

https://www.mathworks.com/help/matlab/ref/sum.html