# index in matrix using loop

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mohamed gamal on 28 Apr 2019
Answered: Kevin Phung on 30 Apr 2019
hi i have an matrix in my code that i want to do some calculation on each index in it so first of all i want to check if that index is greater then 0 then i multiply by area then store it in new varible calld fill
if not i multiple this index with area then store it in variable calld fill
how can i do it

KALYAN ACHARJYA on 28 Apr 2019
It would be helpful to give exact answered, if you can elaborate the question with example.
dpb on 28 Apr 2019
I'd guess it mandatory to give an example or at least clarify because as written the result is the same for either case...
mohamed gamal on 30 Apr 2019
0.500000000000000 0.500000000000000
0.250000000000000 0.500000000000000
-0.500000000000000 -0.500000000000000
like this one and i want to do if the number in the index is + then multiple *AREA+fill
if its - then cut= the numer in matrix*Area +cut

Kevin Phung on 30 Apr 2019
m = [0.5 0.5; 0.25 0.5; -0.5 -0.5] % your sample matrix
f = m(m>0) * A + fill
c = m(m<0) *A + cut
^ this only return the values that meet the positive/neg criteria. If you want to keep the same dimensions then do this:
new_m = m; %copy
new_m(m>0) = m(m>0) * A + fill; %operate on positives
new_m(m<0) = m(m<0) * A - cut;