Avoid division by zero between matrices in MATLAB [duplicate]

问题

This question already has an answer here:

Matlab element-wise division by zero (1 answer)

Closed 3 years ago.

I'm using matlab and I have two matrices :

G =

 1     1     1     1
 1     1     1     1

and the scond:

m =

 4     4     4     4
 0     0     0     0

I want this result :

x =

 1/4     1/4     1/4     1/4
  0       0       0       0

What I did so far is this :

x = G ./ m

But it returns :

x =

 1/4     1/4     1/4     1/4
 NaN     NaN     NaN     NaN

How can I avoid the divison by zero by placing a default value "0" if there is a division by zero ?

回答1:

You can convert the NaNs back to zero:

x = G ./ m;
x(isnan(x))=0;      % thanks to comment by @nkjt

Or, if you have also NaNs in matrix m that you want to save, you can do:

x(m==0)=0;

回答2:

One option would be to preallocate x and then only use division on the parts where m is not zero.

x = zeros(size(m)); % output is same size as m
n = m~=0;  % find indexes
x(n)=G(n)./m(n); 

来源：https://stackoverflow.com/questions/27122456/avoid-division-by-zero-between-matrices-in-matlab