how to vectorized a nested for loop?

Question

0 个投票

i have two for loop and i want to vectorized it . i try a lot to do it but i cannot do it. this is the simple version is let

   Mat = zeros(10)
        for i = 1:10
          for j = 1:10
             Mat(i,j) = exp((i.^5) + j.^2);
          end
        end

Thanks.......

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Answer 1

Jan Orwat 2014-2-13

编辑：Jan Orwat 2014-2-14

0 个投票

Hello Mohammed, there are many ways to vectorize your loops. Check out those examples:

1.

[r,c]=meshgrid(1:10,1:10);
Mat=exp(c.^5+r.^2);

check function meshgrid in help to how it works (type doc meshgrid in commmand window)

2.

Mat=bsxfun(@(A,B)exp(A.^5+B.^2),(1:10)',1:10);

check bsxfun and function_handle

Also, please consider the fact that in your example, and in proposed vectorizations in matrix Mat columns from 4 to 10 have values equal to infinity due to maximum capacity of data precision.

Jan Orwat 2014-2-14

Thanks Mohammed, I've updated the answer. Now it is correct.

Jung Soo Park 2018-2-21

there are two minor errors on mohammed's reply dated 14feb2014. a=zeros(10,10) and isequal(a,Mat1)