how to vectorized a nested for loop?

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.......

Antworten (1)

Jan Orwat
Jan Orwat am 13 Feb. 2014
Bearbeitet: Jan Orwat am 14 Feb. 2014

0 Stimmen

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.

4 Kommentare

thanks for your answer
a = zeros(10);
for i=1:10
for j=1:10
a(i,j) = exp(i.^5+j.^2)
end
end
[r,c]=meshgrid(1:10,1:10);
Mat=exp(r.^5+c.^2);
Mat1=bsxfun(@(A,B)exp(A.^5+B.^2),1:10,(1:10)');
isequal(a,Mat)
result is 0 which means both answers are not same.
mohammed
mohammed am 14 Feb. 2014
i think you just miss one thing that is Transpose of a matrix....... by the way Thanks. and edit the answer so that other can also get benifits...
Jan Orwat
Jan Orwat am 14 Feb. 2014
Thanks Mohammed, I've updated the answer. Now it is correct.
Jung Soo Park
Jung Soo Park am 21 Feb. 2018
there are two minor errors on mohammed's reply dated 14feb2014. a=zeros(10,10) and isequal(a,Mat1)

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