How to sum elements in a matrix rowwise for specific columns only?

I have a matrix X, consisting out of 100 rows and 10 columns. I want to sum up columns 7 to 10 to one single number, yielding a matrix with still 100 rows, but only 7 columns.

Answer 1

[Stephen23]

Where X is your matrix:

Y = [X(:,1:6),sum(X(:,7:10),2)]

[stanley ho]

can you explain what does the 2 stands for in (sum(X(:,7:10),2).

Thank you very much! :)

[Stephen23]

"S = sum(A,dim) returns the sum along dimension dim. For example, if A is a matrix, then sum(A,2) is a column vector containing the sum of each row."

https://www.mathworks.com/help/matlab/ref/sum.html#btv6ok6-1-dim

[stanley ho]

COOL! Thank you so much! :D