Loop for matrix summation

Hello, sorry if my question is stupid, I am a beginner in matlab

I would like to do a 3*3 matrix sumation (element by element). More in detail: I am working with a matlab fuction which output is a 3*3 matrix, the input is 3 column data (strr1,dpr1and rkr1). Then I would like to divide each matrix obtained from the input (280 elements, so I have 280 3*3 matrix) by a scalar, and finally, from that result I would like to sume each matrix to get a single 3*3 matrix (the result of the summation of all matrix calculated by the function). Next, a small script about my problem

Thanks for your attention

strr1=(tw1r1(:,12)); %%input1

dpr1=(tw1r1(:,14)); %%input2

rkr1=(tw1r1(:,16)); %%input3

mtr11w1s=zeros(3,3) %% I created this matriw for storing the final summation

for rr1=1:length(strr1) %%% loop for calculating the 280 3*3 matrix from thre 3 inputs

mtr1=SDR2MT(strr1( rr1),dpr1( rr1),rkr1( rr1)) %%%% Result: 280 3*3 matrix

mtr1n=mtr1/length(tw1r1) %%%%Escalar division for each element of the 3*3 matrix

for z=1:length(mtr1n) %%%% Here I try to do a loop for doing the summation of 280 3*3 matrix

mtr11w1s= mtr11w1s+mtr1n(z)

end

end

Answer 1

[DGM]

I'm not sure what tw1r1 is supposed to be. I'm going to substitute something there.

mytestnumber=37;

mtr11w1s=zeros(3,3);
for rr1=1:numel(strr1) 
	%mtr1=SDR2MT(strr1( rr1),dpr1( rr1),rkr1( rr1)) %%%% Result: 280 3*3 matrixm
	mtr1=ones(3); % i don't have SDR2MT, so this is just a dummy
	mtr1n=mtr1/mytestnumber; 
	for z=1:numel(mtr1n) 
		%mtr11w1s=mtr11w1s+mtr1n(z); % you sure you don't mean to be doing
		mtr11w1s(z)=mtr11w1s(z)+mtr1n(z); % something like this?
	end
end
mtr11w1s

I'm still not really sure if this is doing what you intend it to do. Do you have a written expression for the summation you're trying to do?

Also, as a tip:

a=rand(3,3); [length(a) numel(a)]

shows that if you want to step through all the linear indices of a 2D array, you shouldn't be using length()

ans =
     3     9

[Perez Danny]

DGM, thanks so much for your response.

I have edited my code based on yours, and it ran.

If you want to take an eyed on data I have uploaded it (tw1r1 is an excel table 238*29, it contained 280 rows but after doing some modifications it contains 238 rows)

SDR2MT is a matlab function, not complex, but it helps to get a 3*3 matrix using as input 3 column vectors (strr1,dpr1,rkr1), the output is an individual matrix for each combination of these 3 elements.

[DGM]

I take it that the results are as you expect?

[Perez Danny]

Yeah, results are the expected.

Again, thanks for your help