value replacement in an array

Hi all,

I have a big 2D array and I want to change some of their values. So, I am using A(A==value)=value2. However, it just works for some specific values, for instance it works, when A(A==7.843120581576564e-04) = 1, but I cannot change it when A(A==0.183079763461368)=2. could the decimal be the reason?

Thanks, Yaz

Answer 1

[Star Strider]

My guess is that it’s not an exact match for the value in ‘A’. See Why is 0.3 - 0.2 - 0.1 (or similar) not equal to zero? for an explanation of one possible reason.

[Yazdan Kordestany]

Thanks Star, I checked and you were right. However, I was not able to solve it yet, so I used excel instead and load it on matlab.

[Star Strider]

My pleasure.

If the value already exists in ‘A’ and you want to find other instances of it, use the existing value to compare, since it is likely to have the necessary precision.

Another option is to set a range:

A = 0.183079763461368;
A(A>=0.183079763461367 & A<=0.183079763461369)=2;

This runs without error and sets the single value of ‘A’ here to 2. You will need to experiment with it in your code to see if it does what you want.