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I have to add the values that are inside the matrix called s

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marie
marie on 2 Dec 2012
s= [...
99 99 0.100 0.120 0 0.500 0;
0 0 0 0 0.150 0.120 0;
0.110 0.010 0.010 0 0 0.300 0.100;
0 0.250 0 0.050 0.060 0.100 0.110;
0 0.120 0.040 0 0.500 0.750 1.200];
I have a file with different matrices. I want to write a general code that will add all the values inside this matrix without including the last two in this case 0.750 1.200 and the 99's
so far I have
r=(s(1:5,1:7))
y=sum(r(r<99))
I don't know to remove the last two values as in a general code that will work for the rest of the matrices.
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Accepted Answer

Image Analyst
Image Analyst on 2 Dec 2012
Edited: Image Analyst on 2 Dec 2012
Close. But try it this way if you want to sum everything, except for the last two elements in the last row (kind of a weird restriction, but whatever...), that is less than 99. The key is the transpose which you forgot to do, because if you just do (:) it goes down rows in a column first before it moves over to the next column.
clc;
format compact
format longg
s= [...
99 99 0.100 0.120 0 0.500 0;
0 0 0 0 0.150 0.120 0;
0.110 0.010 0.010 0 0 0.300 0.100;
0 0.250 0 0.050 0.060 0.100 0.110;
0 0.120 0.040 0 0.500 0.750 1.200];
sTransposed = s'; % Note the transpose.
% Get all but the last two columns in the last row.
allButLast2 = sTransposed(1:end-2)
% Now threshold at 99 and sum those below the threshold.
y=sum(allButLast2(allButLast2<99))
The answer:
y =
2.75
  3 Comments
Image Analyst
Image Analyst on 2 Dec 2012
The first 5 elements after the transpose would be the first 5 rows in column 1 but not including the last two elements in column1 of sTransposed. Remember, MATLAB's linear indexing goes down rows in a column first before moving over to the next column, so the first 5 after transposing is sTransposed(1:5, 1). You can extract them to a new array, but you can't remove (delete/eliminate) them unless you convert sTransposed to a cell array.

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