find function with floating points number

Question

sermet 2014-5-8

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/128866-find-function-with-floating-points-number

回答： Star Strider 2014-5-8

distances=[100.2545 120.6632;200.8588 220.4465]
     points_id=[{'p1'} {'p2'};{'p3'} {'p4'}]
    pointfind = @(d) points_id(find(distances == d));
    p = pointfind(120.6632)

%it gives

 p1 = 
   Empty cell array: 0-by-1

%this function only works with integers but I need to work with floating points number.

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Answer 1

Star Strider 2014-5-8

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https://ww2.mathworks.cn/matlabcentral/answers/128866-find-function-with-floating-points-number#answer_136073

在 MATLAB Online 中打开

This revision of pointfind should work:

pointfind = @(d) points_id(find(fix(distances*10^(length(num2str(rem(d,1)))-2))/(10^(length(num2str(rem(d,1)))-2)) == d));

(It obviously all goes on one line, although it wraps here.)

You are dealing with differences in precision between the values stored in distances and the precision in the argument ‘d’ you present to pointfind. The revised version of pointfind truncates the elements of distances to the precision of ‘d’ before it does the comparison. It works with decimal fractions now.