Problem with ismember with certain numbers in a loop

10 次查看（过去 30 天）
Libby M
Libby M 2019-9-3
评论： Star Strider 2019-9-3
Here is the code I have writen, as far as I can see B should alternating 1 and 0 (B=1, 0, 1, 0, 1 etc) but at (as far as I can tell) random points it does not do that. I can't see what I have done wrong and I don't know if I have misunderstood something with "ismember".
I have noticed this with number=0.3250 for example, ismember(number, setcom)=0 but ismember(0.3250, setcom)=1. If however I pause the code type in compand line "number" I get 0.3250 and I get ismember(number, setcom)=0, but if in the comand line I also type "number =0.3250" and then ismember(number, setcom)=1.
I don't understand why it works for most numbers in the loop but not all. Any help would be very much appreciated.
set=[0.125:0.0125:0.5];
setcom=[0.125:0.025:1];
B=zeros(length(set), 1);
for i=1:length(set)
number=set(i);
compare=ismember(number,setcom);
B(i,1)=compare;
end
  2 个评论
KALYAN ACHARJYA
KALYAN ACHARJYA 2019-9-3
set=(0.125:0.0125:0.5);
setcom=(0.125:0.025:1);
B=zeros(length(set),1);
compare=ismember(set,setcom)
Is there loop necessity? Note on Floating points number as answered by @Star
Libby M
Libby M 2019-9-3
Thank you, the loop is necessary for the rest on the code which I didn't put on here but yes are right for what I put up it is not needed. Unfortunately using compare=ismember(set,setcom) still has the same issue as the loop.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Star Strider
Star Strider 2019-9-3
Use ismembertol instead. You are likely dealing with ‘floating-point approximation error’. See Floating-Point Numbers for a full discussion.

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Logical 的更多信息

标签

产品


版本

R2019a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by