problem with making a very simple matrix

Question

Maryam Vaziri Pashkam 2011-9-1

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/14965-problem-with-making-a-very-simple-matrix

Hi I am using 32 bit Matlab 2009b on a macintosh computer with OS 10.6.8. I am running in to a problem in Matlab that I cant figure out the reason. Here is my very simple code: c(:,1)=0.30:0.05:0.95; c(:,2)=0.35:0.05:1.00; find(c(:,2)==0.4)

and here is the answer in the command line: ans =

Empty matrix: 0-by-1

supposedly the c(2,2) should be 0.4 and indeed it looks like it is. But the find command cannot find it. on the other hand it does find 0.3 0.7 etc. I multiplied the c by 1000 and looks like some of the values in it will be 300, 500 etc and some other values like 0.4 will be 400.000. I am not sure what is going on here. Is this a known bug? is there a fix for it?

Thanks, Maryam

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Arturo Moncada-Torres 2011-9-1

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/14965-problem-with-making-a-very-simple-matrix#answer_20347

The problem is that you are trying to compare floating point numbers. This is clearly explained in the MATLAB FAQ. Also check this recent previous thread which addresses the same problem.