# Matrix divison or calculating slope

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Suzana Kralj on 21 May 2019
Commented: Suzana Kralj on 22 May 2019
Hi everyone!
I am new user of Matlab and I have a problem with basic operations.
So,I have two matrix
tc=[0 0.5 1 2 3 4 5 10 15 20 30 45];
hc=[0.248 0.248 0.248 0.248 0.248 0.248
0.243 0.244 0.246 0.248 0.247 0.248
0.215 0.236 0.241 0.247 0.246 0.248
.....................................];
the thing I need to do is: for each column in matrix hc divide the difference of second and first row with the difference of second and first member of matrix tc, and in next step do the same for third and second member. (this is actually calculating the slope for each experimental data).
For example: slope=(hc(1,1)-(hc(2,1)))/(tc(1,2)-tc(1,1)) or with data (0.248-0.243)/(0.5-0)
My idea was to do that with for loops:
slope=zeros(12,6);%initialization of matrix
for i=1:12 %there are 12 rows in hc full data
for j=1:6
slope(i,j)= ((hc((i),j))-(hc(i+1),j)))/((tc(1,(j+1)))-(tc(1,j)));
end
end
but it's not working. So I would need your help.

Are Mjaavatten on 22 May 2019
Edited: Are Mjaavatten on 22 May 2019
There is a syntax error with your use of parentheses. Also, the slope for the last row is not defined. This should work:
nrows = 3; % Set nrows to 12 for your full data set
slope=zeros(nrows-1,6);
for i=1:nrows-1
for j=1:6
slope(i,j)= (hc(i,j)-hc(i+1,j))/(tc(1,j+1)-tc(1,j));
end
end

#### 1 Comment

Suzana Kralj on 22 May 2019
It works!
Thank You really much!